3117 Swimming Pools and Electric Space Heating the Case for Coverage by the BCA
Transcript of 3117 Swimming Pools and Electric Space Heating the Case for Coverage by the BCA
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FINAL
Swimming pools and
electric space heating
The case for coverage by the Building Code of
Australia
January 2009
Prepared for the Australian Building Codes Board
by
George Wilkenfeld and Associates
GEORGE WILKENFELD AND ASSOCIATES Pty Ltd
ENERGY POLICY AND PLANNING CONSULTANTSPO Box 934 Newtown NSW 2042 Sydney Australia
Tel (+61 2) 9565 2041
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Contents
Summary ........................................................................................................................... 3
Swimming pools ....................................................................................................... 3
Public Pools .............................................................................................................. 4
Electric Resistance Space Heating ........................................................................... 71. Background................................................................................................................... 9
1.1 The BCA and Energy- and Water-efficiency ........................................................ 9
1.2 This Paper ............................................................................................................... 9
Swimming pools ..................................................................................................... 10
Electric Resistance Space Heating ......................................................................... 10
1.3 Swimming Pools ................................................................................................... 10
2. Domestic Swimming Pools ........................................................................................ 12
2.1 Number, and type of pools .................................................................................. 12
2.2 Energy and Water Impacts .................................................................................. 15
2.3 Elements of energy use ........................................................................................ 16
Pumping .................................................................................................................. 16
Sanitisation, timers and controllers ........................................................................ 17
Heating ................................................................................................................... 17
2.4 Standards and levels of efficiency....................................................................... 18
2.5 Potential Role for BCA ....................................................................................... 19
3. Shared and Public Pools ............................................................................................. 21
3.1 Type and number of pools ................................................................................... 21
3.2 Energy and Water Impacts .................................................................................. 22
3.3 Elements of energy use ........................................................................................ 24
Pool water management and conditioning ............................................................. 24
Heating and Ventilation of Pool Buildings ............................................................ 25User amenities ........................................................................................................ 25
3.4 Potential Role for BCA ....................................................................................... 26
4. Fixed Electric Resistance Space Heating ................................................................... 27
4.1 Types of Fixed Electric Resistance Heating......................................................... 27
Underfloor (slab) heating..................................................................................... 29
Heat banks .............................................................................................................. 30
4.3 Potential Role for BCA ....................................................................................... 31
References .................................................................................................................. 34
Appendix 1: California Title 24 Requirements: Swimming Pools............................. 35
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Summary
The Building Code of Australia (BCA) is becoming increasingly involved in areas of
design that impact on the on-going energy use of buildings. The main rationale is to
address market failures. Many of the parties who plan and construct new buildings have
a reduced incentive to incorporate design features and services which could cost-
effectively reduce lifetime operating costs, because it will be the ultimate buyer,
occupant or tenant who will meet those costs.
The impending implementation of the Australian Governments Carbon Pollution
Reduction Scheme (CPRS) is expected to lead to higher energy prices. This will
strengthen the case for the BCA to incorporate provisions which increase the energy-
efficiency of buildings, because the financial costs of the failure of the market to
provide the most cost-effective level of building efficiency will be higher. The BCA
could raise the stringency of standards, or add provisions for building types and services
not yet covered.
This study was commissioned by the Australian Building Codes Board (ABCB) Office
to review the case for BCA coverage of:
swimming pool and spa pool energy use (and the emissions related to that energyuse); and
fixed electric resistance space heating.Swimming pools
Swimming pools are energy- and water-intensive structures. In 2007 about 945,000Australian households (11.7% of the total) had a swimming pool, and swimming pools
and spa pools accounted for about 3.3% of total household electricity use: more than
clothes dryers and dishwashers combined. In the homes which had a pool, it was almost
always the largest single electricity user, averaging 1,930 kWh per year, compared with
720 kWh per year for refrigeration. The great majority of pool electricity use was for
filtration pumping.
Pools and spas in hotels typically account for 4% to 8% of the total building energy use,
and in apartment buildings they typically account for 10% to 20% of common area
energy use. Aquatic centres are among the most energy-intensive of building types,
with energy per floor area typically 5 times that of office buildings.
These statistics indicate that including the energy use or energy-efficiency of swimming
pools in the BCA deserves consideration.
Constructed swimming pools or spa pools are usually subject to local government
planning approval, which represents a point at which BCA compliance could be
enforced. However, council requirements vary for stand-alone spa pools brought to site
as complete assemblies they may be listed as a complying development, exempt
development or not specifically mentioned at all. Therefore the full effectiveness of
any BCA provisions related to stand-alone spa pools is subject to uncertainty.
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There are no accepted measures or standards of overall energy performance for
domestic swimming pools, and performance can vary significantly with the owners
settings and preferences. Therefore there is no basis to adopt energy design standards
for entire swimming pool systems, or to test whether those standards are achieved in
designs or even in post-construction operation.
It is however possible to set performance standards for selected pool components, and
to require design features which are known to lower energy use in operation. The NSW
BASIX scheme requires a BASIX certificate for swimming pools and/or spas with a
combined volume of 40,000 litres or more. The applicant must enter data on volume,
location (indoors/outdoors), method of water heating if any, and whether outdoor pools
are shaded or equipped with a pool cover. Electric resistance heating is not permitted for
swimming pools.
The CaliforniaEnergy Efficiency Standards for Residential and Nonresidential
Buildings go considerably further than BASIX, in that they impact on the actual
hydraulic design of the pool, pump efficiency, pump control strategy and heaterefficiency.
An Australian Standard for testing and energy efficiency rating and labelling of
swimming pool pumps is near completion. The Standard will also contain a minimum
energy performance standard (MEPS) level which will be relatively low, at least
initially. Subject to passing a regulatory impact assessment, it is envisaged that the
Standard will be made mandatory under State legislation, in the same way as other
appliance labelling and MEPS standards. The Commonwealth-State Equipment Energy
Efficiency Program has also undertaken to sponsor the development of a method of test
and a rating system for gas pool heaters.
There is a case for including the following provisions in the BCA at the earliest
opportunity (subject to formal cost-benefit analysis):
1. Requirements for pipe sizes and layout which reduce resistance to water flow,and so reduce the energy requirement for filtration pumping (eg 50 mm
minimum pipe diameters and gradual bends rather than 90elbows);
2. Prohibition of the use of electric resistance water heating for swimming pools.(As very few electric resistance heaters are used on swimming pool heating, this
is large a preventative measure). This leaves the alternatives of unboosted solar,gas and heat pump water heating;
3. Prohibition of the use of electric resistance water heating for stand-alone spapools (other than single-phase electric resistance heaters built into the
recirculation systems of fully assembled stand-alone spa pools, or electric
boosting of solar water heaters). This leaves the alternatives of solar, gas and
heat pump water heating;
4. A requirement that all heated spa pools meet a specified level of thermalinsulation, and be fitted with removable covers that also meet a specified level
of thermal insulation. This should apply to both stand-alone and constructed spa
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pools, if these can be covered by the BCA (if not, appliance energy efficiency
standards should be developed for stand-alone spas);
5. A requirement that all swimming pools equipped with heating (of any type) befitted with a removable pool cover, whether the pool is indoors or outdoors;
6. A requirement that all swimming pools and spa pools be installed with one ormore user-adjustable timers or other control devices which limit or manage the
hours of pump operation. (As very few pumps are installed without timers, this
formalises prevailing practice).
There may be a case in future for including the following provisions in the BCA:
7. Minimum energy efficiency levels for pump-units, that may be higher than thegeneral MEPS levels adopted for those products. This should be considered
once mandatory energy labelling and MEPS is implemented for pump-units, and
sufficient information is collected on the sales-weighted energy-efficiency ofpump-units installed in new pools;
8. Minimum energy efficiency levels for gas pool heaters, that may be higher thanthe general MEPS levels adopted for those products. This should be considered
once mandatory energy labelling and MEPS is implemented for gas pool
heaters, and sufficient information is collected on the energy-efficiency of pool
heaters units installed in new pools;
9. Requirements for pump-unit configurations and control strategies to limit powerand rates of flow and to prevent the installation of over-sized filtration pumps
which would operate at low efficiency much of the time (as in California).
These issues should be reviewed from time to time as information accumulates.
Public Pools
Public pools, which are open to all users, range from single unheated outdoor
swimming pools run by a municipality to multiple Olympic standard pools enclosed
within large buildings, or aquatic centres.
Shared pools are typically controlled by a buildings owner or body corporate, and arefor the use of any authorised person: eg swimming pools in the common areas of
apartment buildings or hotels, where the condition of use may be tenancy of an
apartment or being a guest at the hotel.
Although there are no comprehensive data, it is estimated that there could be 1,000 to
1,500 public pool complexes in Australia, many with more than one swimming pool. It
is also estimated that there could be 8,000 to 10,000 shared swimming associated with
apartment buildings, hotels, clubs and fitness centres.
Shared and public pools use energy for the same main purposes as domestic pools:
water filtration, sanitisation and heating. However, the amount of energy used per pool
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is much higher because average water volume is higher, bather loads are high and the
sanitisation standards for public pools have to meet public health regulations.
In effect public and shared pools need to be sanitised and filtered continuously while
open to the public, as distinct from domestic pools, where filters and sanitisers only
need to operate 15% to 25% of the time, even in the swimming season.
The information about water and energy use in public pools in Australia is rather
limited, although several studies currently under way should improve this situation
during 2009. Information about shared pools in hotels and apartment buildings is even
more limited.
In general, the same energy and water uses are present in public pools and the buildings
which house them as for domestic pools, but on a much larger scale and designed for
high intensity of use.
There are however several important differences in design approach:
Public pool design tends to involve engineers, architects and other buildingprofessionals, whereas domestic pools tend to be designed by builder-packagers;
Many clients commissioning public pools are well aware of the high operating costs,and will instruct designers accordingly, whereas very few domestic pool clients are
aware of this;
Public pools must meet a range of stringent and regularly enforced health standards,some of which are quite prescriptive in terms of sanitisation and water turnover,whereas the standards for domestic pools are in effect advisory and not enforceable;
Many public pools are housed in buildings, or parts of buildings, which have highservice requirements and energy use of their own and interact with the general
building services in complex ways (some of which offer opportunities, eg use of
waste heat). Very few domestic pools are in this situation.
There is a case for including the following provisions in the BCA at the earliest
opportunity (subject to formal cost-benefit analysis):
10. Definition of a distinct class of non-domestic swimming pools and spa poolsthat correspond to the definition of public pools used in health regulations;
10. Prohibition of the use of electric resistance water heaters for public swimming
pools or spa pools. The alternatives would include solar (unboosted, electric-
boosted or gas-boosted), gas, heat pump or waste heat;
11. A requirement that all public spa pools be fitted with insulating covers and have
a minimum level of thermal insulation;
12. A requirement that all public swimming pools equipped with heating (of any
type) be fitted with a removable pool cover, whether the pool is indoors oroutdoors;
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As nearly all public pools would have special design requirements which are likely to
involve engineers or other specialists, general design provisions relating to pipe sizes or
controls, which are appropriate for domestic pools, are not appropriate for public pools.
There are at present no general Australian energy or water performance standards forpublic pools, for buildings housing public pools (eg Class 9) or the parts of buildings
housing public pools (eg parts of Class 2 or 3). There are several projects under way to
gather data on which such performance standards could be based.
Even if performance standards were developed, it would also be necessary to develop
methods of predicting performance so that compliance with those standards could be
established. It may then also be possible to establish deemed to satisfy provisions: eg
the recovery of heat from moist air ventilated from the pool hall.
There may be a case for including such provisions in the BCA in future, and these
issues should be reviewed from time to time as information accumulates.
Electric Resistance Space Heating
Electric resistance heating is currently the most greenhouse gas-intensive means of
space and water heating, even though it is close to 100% efficient at the point of
conversion. This is because the great majority of electricity generated in Australia is
from the combustion of coal, leading to high emissions and low conversion efficiency at
the power stations. Despite the CPRS, the average emissions intensity of electricity
supplied in Australia is still projected to be about 75% of todays levels by 2030.
Electric resistance heaters have the advantage of flexibility of location, since no pipes or
flues are necessary. The relatively low capital costs can make electric resistance space
heating attractive to home builders where some form of fixed heating is required. The
main disadvantages are high running costs and high greenhouse gas-intensity.
Electric heaters up to 2.4 kW output can be plugged into a power-point, whether or not
the heater is fixed to the structure or portable. Larger capacity units need fixed wiring,
so need to be installed by a qualified person. The effectiveness of BCA coverage of
plug-in fixed electric heaters is likely to be limited, because any provisions can be easily
circumvented by simply fixing the heaters after completion and plugging them in.
The only types of electric resistance heater that could be effectively covered are:
Heaters which are part of the building fabric, eg physically integrated into the floor,wall or ceiling, rather than fixed to their surface; and/or
Hard-wired heaters, which may not be connected to the electricity supply by astandard power point, because they draw more than 10 amps, and/or require a 3-
phase supply, or for safety reasons.
These definitions would cover electric slab and underfloor heating, and heat banks, both
of which are relatively rare in existing buildings, and probably even more so in newones. It has been suggested that if electric storage water heaters are excluded from new
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dwellings on the grounds of greenhouse gas-intensity, then so should electric storage
space heaters. This does not necessarily follow.
Water heaters deliver a highly standardised service so qualitative differences between
types and energy forms are small. As users have no strong preferences (other than not
running out of hot water), they are usually content to leave the decision to the builder orother intermediary: this accounts for the split incentive market failures which the BCAs
requirements for water heaters are intended to address.
Space heaters, on the other hand, deliver outputs that are qualitatively different. People
have strong preferences for convection, conduction or radiant forms of heating, for real
flames (or flame effects), and even for different fuels. It is especially likely that
preferences will come into play when selecting electric heaters that are moreexpensive
to buy and install (as is the case with slab heating and heat banks) and less costly to run.
This is the opposite of the water heating case, where lack of user involvement tends to
lead to the outcome with the lowest capital cost but higherrunning cost.
The diverse and specialised nature of space heating also means that there are no direct
non-electric alternatives for many electric resistance heaters, unlike electric water
heaters, where the obvious alternatives are solar-boosted electric and heat pumps even
before considering other fuels.
While there does not appear to be a case for the BCA to set performance requirements
that would prohibit the installation of fixed and hard wired electric resistance heating,
there may be a case for requiring design elements and features which would reduce the
risk of energy waste from such systems. The BCA already requires mandatory under-
slab and slab-edge insulation where in-slab heating is to be installed.
Other provisions could include:
14. For in-slab and under-floor electric resistance heating:
a. mandatory zoning, so that heating to each space can be switchedseparately
b. all zones to be controllable by timers or programmable controllers andthermostats
c. maximum power loads, eg 110W/m2for living areas and 150 W/m2forbathrooms.
15. All heat banks to have a mandated maximum rate of heat loss into the space (eg
200W) when fully charged and when all baffles are closed and all fans are off, to
reduce the risk that heat would have to be vented from the room under warmer
than expected conditions.
*****
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1. Background
1.1 The BCA and Energy- and Water-efficiency
The Building Code of Australia (BCA) is becoming increasingly involved in areas ofdesign that impact on the on-going energy use of buildings. The main rationale is to
address market failures. Many of the parties who plan and construct new buildings have
a reduced incentive to incorporate design features and services which could cost-
effectively reduce lifetime operating costs, because it will be the ultimate buyer,
occupant or tenant who will meet those costs.
Because of their longevity, buildings also represent a social good. While no single
occupant or owner may be in a position to recover all the benefits of initial investments
in efficiency, the total benefit accruing to all successive owners, users and occupants
over the buildings lifetime can justify higher initial investment in efficient resource
use.
For these reasons, the BCA has incorporated a number of requirements related to the
energy-efficiency of domestic and non-domestic buildings, commencing with minimum
thermal performance standards, water heater requirements and (for non-domestic
buildings), lighting and some mechanical services. The extension of lighting standards
to Class 1 buildings and the revision of water heater provisions are also possibilities for
the future.
The impending implementation of the Australian Governments Carbon Pollution
Reduction Scheme (CPRS) is expected to lead to higher energy prices. This will
strengthen the case for the BCA to incorporate provisions which increase the energy-efficiency of buildings, because the financial costs of the failure of the market to
provide the most cost-effective level of building efficiency will be higher. This could
mean raising the stringency of standards, or adding provisions for building types and
services not yet covered.
With the establishment of the CPRS, national greenhouse gas emissions will be capped
(at levels still to be determined), so greater energy efficiency or the use of less
greenhouse-intensive form of energy in new buildings are not likely to reduce emissions
further below the cap. Reducing the demand for energy and hence emission permits,
however, will lower the adjustment costs for the economy as a whole, and financially
benefit building owners and occupants by limiting their exposure to rising energy
prices. As energy costs will increasingly reflect the greenhouse-intensity of energy
sources, the projected greenhouse impact of building services is still one of the most
useful metrics for comparing options.
1.2 This Paper
This study was commissioned by the Australian Building Codes Board (ABCB) Office
to review the case for BCA coverage of:
swimming pool and spa pool energy use (and the emissions related to that energyuse); and
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fixed electric resistance space heating.Swimming pools
This study covers both domestic and non-domestic swimming pools and spa pools. It
considers:
The estimated magnitude of energy use and related emissions; Categories of swimming pools and swimming pool equipment; Common design approaches used in swimming pools and spa pools; The need for and practicality of including provisions related to design and energy
use in the BCA.
Electric Resistance Space Heating
There may be merit in preventing the installation of electric resistance water heating in
new buildings, on the grounds of the high associated greenhouse gas emissions. The
same principles and arguments could also be applied to electric resistance in-slab and
underfloor heating, and also to fixed electric space heating, where a resistance element
heats air within a heating unit that is fixed to the building structure.
This paper review the case for, and practicality of, excluding these forms of heating
through provisions in the BCA.
1.3 Swimming Pools
The BCA defines a swimming pool as any excavation or structure containing water and
used principally for swimming, wading, paddling, or the like, including a bathing or
wading pool, or spa.
Australian Standards1define a swimming pool as follows:
A swimming pool includes any waterslide, wave pool, hydrotherapy pool or
other similar structure designed for human use, other than
(a) a spa pool or spa bath (unless part of the pool system); or
(b) a tidal pool or other similar structure where water flows in and out according
to the operation of natural forces.
A spa pool is defined as:
A water-retaining structure designed for human use
(a) that is capable of holding more than 680 litres of water; and
1These definitions are used in a number of Standards, including the forthcoming Performance ofElectrical Appliances Swimming Pool Pump-Units(currently DR 8632).
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(b) that incorporates, or is connected to, equipment that is capable of heating any
water contained in it and injecting air bubbles or water into it under pressure so
as to cause water turbulence.
Domestic swimming pools fall within Class 10 of Volume 2 of the BCA: non-habitable
buildings and structures. At present BCA Volume 2 covers access arrangements forswimming pools (ie enclosures and gates) and measures to avoid the entrapment of
persons in the water recirculation system.
Swimming pools and spa pools that are parts of non-domestic buildings (eg Class 2 or
3) are covered by Volume 1 of the BCA, which covers access arrangements, measures
to avoid entrapment of persons in the water recirculation system, and drainage and
disposal of water. An aquatic centre could be a stand-alone Class 10 structure, or could
consist of one or more swimming pools within a Class 9 (Assembly) building.
Swimming pools are energy- and water-intensive structures. Where domestic
swimming pools are installed they usually represent the highest single consumer ofelectricity in the household. Pools and spas in hotels typically account for 4% to 8% of
the total building energy use, and in apartment buildings they typically account for 10%
to 20% of common area energy use. Aquatic centres are among the most energy-
intensive of building types, with energy per floor area typically 5 times that of office
buildings (Carbon Trust 2008).
These statistics indicate that including the energy use or energy-efficiency of swimming
pools in the BCA deserves consideration.
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2. Domestic Swimming Pools
2.1 Number, and type of pools
The ABS reports that in 2007 about 945,000 Australian households (11.7% of the total)had a swimming pool (Figure 1, Figure 2). Swimming pool ownership is projected to
rise to nearly 14% by 2020, by which time there would be about 1.24 million pools
(EES 2008). The rate of pool ownership is highest in the warmer parts of Australia
(Queensland, NT and WA) and lowest in the coolest parts (Victoria, the ACT and
Tasmania). The rate of pool ownership in NSW appears to be falling slowly, although
the State still has more pools than any other (Figure 3).
A small proportion of swimming pools have an inbuilt spa pool, ie one that shares a
water recirculation system with the main pool. Separate or stand-alone spa pools are
also becoming more common. About 1.4% of homes had a stand-alone spa pool in
2007, and this is projected to rise to about 1.7% on 2020.
The distinction between swimming pools and spa pools are not always clear. In some
cases householders who would otherwise have installed a swimming pool are now
installing spa pools, because declining block sizes and larger house floor areas limit the
land area available for pools. Smaller swimming pools (and larger spa pools) are
sometimes fitted with powerful swim jet pumps which create sufficient water flow for
swimming on the spot.
Although swimming pools are generally larger (averaging about 50,000 litres) there are
now spa pools of up to 25,000 litres, about the same volume as small swimming pools.
About 88% of swimming pools are in-ground, while the great majority of stand-alonespa pools are above ground (BIS 2006). About three quarters of in-ground pools are in-
situ concrete and the rest fibreglass; usually rigid liners brought to site and buried.
Above-ground swimming pools may be constructed using flexible liners, or brought to
site as rigid assemblies. Above-ground spa pools are usually factory-made assemblies
complete with pumps, heaters and decorative external cladding.
Most domestic swimming pools are installed some time after the construction of the
dwelling. Two thirds of pool owners reported having made the decision to install their
pool, while a third reported that it had come with the house (BIS 2006).
Constructed swimming pools or spa pools are usually subject to local government
planning approval, which represents a point at which BCA compliance could be
enforced. However, council requirements vary for stand-alone spa pools brought to site
as complete assemblies they may be listed as a complying development, exempt
development or not specifically mentioned at all.2 Therefore the full effectiveness of
any BCA provisions related to stand-alone spa pools is subject to uncertainty.
2Swimming Pools and Spas Association of NSW (SPASA), personal communication, January 2009.
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0%
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Figure 1 Historical and projected ownership of swimming pools, Australia
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Figure 2 Number of swimming pools and stand-alone spas, Australia
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0%
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Figure 3 Ownership of swimming pools by State
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Figure 4 Energy use of domestic swimming pools and spa pools
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2.2 Energy and Water Impacts
The main uses of energy in swimming pools and spa pools are:
Filtration pumping: about 90% of swimming pools have a filtration pump whichoperates for several hours each day as long as the pool is filled. Most users extend
pump operating hours during the swimming season and shorten them during the off-
season.
Sanitisation: about 60% of all pools (and the great majority of new pools) have anelectrolytic cell which breaks salt added to the water down to free chlorine. A small
proportion of pools use other means of automatic sanitisation such as chlorine
dosers, and the remainder rely on manual dosage of granular or liquid chlorine.
Water heating: about a third of all swimming pools (and all spa pools, by definition)have some form of heating. The most common form of heating for swimming poolsis solar water heating, which uses energy for pumping (unlike solar domestic hot
water, there is no boosting). The most common form of inbuilt heating for smaller
spa pools is electric resistance heating, and larger spa pools often use natural gas
water heating.
Other energy uses include spa jets and swim jets (generally used only when the pool is
occupied), timers and control gear, underwater lighting and maintenance uses such as
pool cleaning. Most cleaning devices rely on the pressure of the water flow though the
filtration system, but about 3% of swimming pools have separate cleaners with their
own motors.
It is estimated that in 2008 swimming pools and spa pools accounted for about 3.3% of
total household electricity use: more than clothes dryers and dishwashers combined. In
the homes with a swimming pool, it was almost always the largest single electricity
user, averaging 1,930 kWh per year, compared with 720 kWh per year for refrigeration.
The great majority of pool electricity use was for filtration pumping (Figure 4).
Dedicated pool and spa heating accounted for about 1.8% of domestic gas use. Less
than 3% of swimming pools (representing less than 0.4% of households) have gas pool
heaters, but these tend to be very large energy consumers. The breakdown of heating
energy use in stand-alone spa pools, or the share that comes from inbuilt heaters as
distinct from dedicated external heaters or from general domestic water heaters is notknown.
Swimming pools and spa pools are significant consumers of water. Swimming pools
are rarely emptied completely, but they are subject to water loss through evaporation
and have to be topped up regularly in hot weather. Water is also lost to the drain during
the filter cleaning and backwashing process. A typical 50kl swimming pool in
Melbourne may need 20 to 30 kl of top-up water in a typical year in hotter parts of
Australia, more than the full volume of the pool will be lost each year (GWA 2006).
Evaporation can be reduced by partially screening the pool from wind or by covering
the pool when not in use. About 14% of pools have a cover, but half the owners report
that they rarely or never use it (BIS 2006).
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Spa pools are much smaller and generally lose very little water to evaporation, either
because they stand empty or, if they are left full, they are often covered to conserve
heat. However, many are emptied and refilled on a regular basis. BIS (2006) reported
that spa pool owners refilled their pools over 60 times per year on average. Even if the
smaller spas were refilled more frequently than the larger ones, annual water use per spa
could well be over 100 kl per year, or twice the volume of a full size swimming pool.
2.3 Elements of energy use
Pumping
Most of the electricity used in swimming pool operation is for pumping water through
filters or through solar collectors. Separate pumps may also be used for pool cleaners or
to circulate water through features such as waterfalls, but these tend to be required only
for short periods.
The keys to reducing the pumping energy use of a pool are:
Design the pool to minimise resistance to water flow. In general, this means usinglarger diameter pipes and fewer and more gradual bends. The choice of filter can
also be important: cartridge filters have less design flow resistance than sand filters
and are easier to clean, so are likely to be kept in a condition of lower flow
resistance. Preliminary cost-benefit modelling indicates that substituting a cartridge
filter for a sand filter is cost-effective, and saves 80 to 90 kWh per year. Changing
to 50mm piping and 135rather than 90bends, or larger radius curves, saves
between 60 and 250 kWh per year, depending on the filter and the poolconfiguration.
Matching the pump characteristics to the pool: the ideal is to turn the pool over (iecirculate the entire volume) at least once per day, and doing this at low flow rates
uses less energy per litre pumped than at high flow rates. Most pumps are single
speed, but there are two speed pumps which default to the lower speed for normal
pumping, but can be used at high speed for cleaning or backwashing. Variable speed
pump controllers which factor in the condition of the filters and the time needed to
sanitise the pool have also been introduced, but are expensive.
Use the most energy-efficient pump-unit of the models suitable for that particularpool.3 Standards Australia is currently developing a method of test for pool pump-units and a rating method to indicate relative energy efficiency, using the same star
rating label format as is used for household appliances.4
3A pump-unit is an electric motor coupled to a hydraulic pump. The energy efficiency of the unit
depends on both the efficiency of the motor and the efficiency of the pump, but can only be accurately
determined when the complete pump-unit is tested under a hydraulic load.4The standard, being developed by Committee EL-015-25, is expected to be published in the first half of2009.
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Sanitisation, timers and controllers
Most pool pumps, sanitisers and cleaners are operated by timers or controllers, which
have a small standby power consumption. Electrolytic cells and chlorine dosers
themselves have relatively low energy use (typically 150-200W for a cell, compared
with about 750-1,500 W for a filtration pump). However, the cell cannot operatewithout a flow of water, so pump operation is sometimes extended for sanitisation
purposes, even after there has been sufficient circulation for the filter to remove solids.
Heating
About 31% of swimming pool in NSW, Vic, Qld, SA and WA have some form of
heating, ranging from 75% in Victoria to 17% in WA (BIS 2006). The popularity of
heating appears to be growing: over half the pools completed within the past 2 years
report some form of heating, compared with about a quarter of older pools.
The main forms of heating installed in swimming pools up to 5 years old are:
Solar (over 90% of pool heating installations): this is the most energy-efficient formof pool heating, because no thermal input is required, only pumping energy. It is
more energy-efficient to have separate pumps for the filtration and the solar heating
circuits, and over three quarters of installations use a two-pump system. In the rest,
the energy use of the main filtration pump can be greatly increased because it would
need to be oversized to circulate the water through the solar collectors, and because
the operating hours would be extended beyond filtration needs.
Gas (about 7% of pool heating installations): these are typically large recirculatinginstantaneous water heaters with inputs ranging from 58 MJ/hr (16 kW) to about430MJ/hr (120 kW) compared with 80 to 200 MJ/hr for domestic instantaneous
gas water heaters. At present there are no energy labelling or minimum energy
performance standards for gas pool heaters, but the scope for these is being
investigated by the government Equipment Energy Efficiency (E3) program.
Electric heat pumps (about 3% of pool heating installations).Electric resistance pool heaters are also available (typically 36-40 kW, 3-phase)
although now rarely used in domestic installations.
Solar pool heaters operate in a different way from other pool heaters because their
delivery temperature is limited to about 38C and this is only achieved during the
warmer months, compared with 60-80C at any time for other heaters. They can extend
the summer swimming season (especially when used with a pool cover) but do not
enable year-round swimming.
Stand-alone spa pools are all heated. Small to medium spas usually have a single phase
electric resistance heater up to about 5 kW on the filtration circuit. Larger spas may be
connected to an external recirculating gas pool heater. Smaller spas may be filled from
non-recirculating external water heaters such as a domestic gas instantaneous heater
installed for the purpose, or from the general house supply, in which case the energy
efficiency of the water heating will be determined by the domestic water heater.
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Non-recirculating water heaters add new hot water to the spa, so if there is water in it
already some will have to be wasted, along with any heat and chemicals it may still
contain. In any case, the better insulated the spa and its cover, the more heat will be
retained until the next use, so less heat (and less water) will need to be added.
2.4 Standards and levels of efficiency
There are no accepted measures or standards of overall energy performance for
domestic swimming pools. Performance can vary significantly: a field trial which
swapped several pumps between several pools found that filtration pumping energy
varied from 2.9 to 12.1 kWh per 50,000 litres pumped, with most of the variation due to
the owners settings and preferences (solar hot water pumping and chlorinator energy
also varied). For the same pool, energy use could vary from 2.2 to 13.4 kWh per 50,000
litres pumped, under different pumps and settings. The lowest energy requirement was
for a dual speed pump operating at the lower speed.
Therefore there is no basis to adopt energy design standards for entire swimming pool
systems, or to test whether those standards are achieved in designs or even in post-
construction operation.
It is however possible to set performance standards for selected pool components, and
to require design features which are known to lower energy use in operation. This is the
approach taken in the CaliforniaEnergy Efficiency Standards for Residential and
Nonresidential Buildings (see extract at Appendix 1).
It is also being used to some extent in Australia. The BASIX scheme in NSW, for
example, requires a BASIX certificate for swimming pools and/or spas with a combined
volume of 40,000 litres or more. The applicant must enter data on volume, location
(indoors/outdoors), method of water heating if any, and whether outdoor pools are
shaded or equipped with a pool cover. Electric resistance heating is not permitted for
swimming pools.
The certificate may carry requirements such as:
A pool pump timer must be installed (California also has this requirement, but setsadditional capabilities for the timer);
A spa pump timer must be installed; A spa cover must be installed (California also has this requirement, with specified
insulation values where electric resistance heating is used);
A rainwater tank must be installed for topping up the pool (there must be a rainwatertap within 10m of the pool and/or spa); the volume of the rainwater tank (if
required) depends on the nominated roof area draining to it, and whether a pool
cover and shading have been nominated.
Californias swimming pool requirements go considerably further than BASIX, in that
they impact on the actual hydraulic design of the pool, pump efficiency, pump control
strategy and heater efficiency:
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The pool must be designed for less than a maximum flow rate: this is intended tomake the hydraulics compatible with lower power and lower speed pumps or modes
of operation, which are more energy-efficient.
Pumps should be multi-speed (with default to lowest speed) or separate auxiliariesshould have separate pumps: this is intended to avoid large, high power pumpsoperating at part loads well below their optimum efficiency point. Auxiliary pool
loads that require high flow rates such as spas, pool cleaners, and water features,
should be operated separately from the filtration to allow the filtration flow rate to
be kept to a minimum.
Electric resistance heating may not be used for pools except in conjunction withsolar or recovered heat, or with spa pools which meet specified levels of thermal
insulation.5
Only those pool pumps, gas pool heaters and heat pump pool heaters may be usedwhich are registered as meeting California appliance efficiency standards.
Where solar heating is not installed, connections shall be installed to allow for thefuture addition of solar heating equipment.
The issues which the California regulations seek to address are also present in Australia.
Most pool builders use 40mm pipes and 90bends, even though increasing pipe sizes to
50mm and using 135bends is the single most cost-effective way to reduce the
pumping energy needed.
Also, there is a tendency for pool builders and designers to oversize: to recommend andinstall high power, high-flow pumps rather than lower power, lower flow, lower speed
pumps. This also carries an energy penalty.
Some of the elements on which the California regulatory approach is built are also
present in Australia. An Australian Standard for testing and energy efficiency rating
and labelling of swimming pool pumps is near completion. The Standard will also
contain a minimum energy performance standard (MEPS) level which will be relatively
low, at least initially. Subject to passing a regulatory impact assessment, it is envisaged
that the Standard will be made mandatory under State legislation, in the same way as
other appliance labelling and MEPS standards. Multi-speed and variable speed pumps
can generally obtain a higher star rating than single-speed pumps.
The Commonwealth-State Equipment Energy Efficiency Program has also undertaken
to sponsor the development of a method of test and a rating system for gas pool heaters.
2.5 Potential Role for BCA
There is a case for including the following provisions in the BCA at the earliest
opportunity (subject to formal cost-benefit analysis):
5There are lists of complying spas, pool pumps, gas pool heater and heat pump pool heaters athttp://www.energy.ca.gov/appliances/database/excel_based_files/Pool_Products/
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7. Requirements for pipe sizes and layout which reduce resistance to water flow,and so reduce the energy requirement for filtration pumping (eg 50 mm
minimum pipe diameters and gradual bends rather than 90elbows);
8. Prohibition of the use of electric resistance water heating for swimming pools.(As very few electric resistance heaters are used on swimming pool heating, thisis large a preventative measure). This leaves the alternatives of unboosted solar,
gas and heat pump water heating;
9. Prohibition of the use of electric resistance water heating for stand-alone spapools (other than single-phase electric resistance heaters built into the
recirculation systems of fully assembled stand-alone spa pools, or electric
boosting of solar water heaters). This leaves the alternatives of solar, gas and
heat pump water heating;
10. A requirement that all heated spa pools meet a specified level of thermalinsulation, and be fitted with removable covers that also meet a specified level
of thermal insulation. This should apply to both stand-alone and constructed spa
pools, if these can be covered by the BCA (if not, appliance energy efficiency
standards should be developed for stand-alone spas);
11. A requirement that all swimming pools equipped with heating (of any type) be
fitted with a removable pool cover, whether the pool is indoors or outdoors;
12. A requirement that all swimming pools and spa pools be installed with one or
more user-adjustable timers or other control devices which limit or manage the
hours of pump operation. (As very few pumps are installed without timers, this
formalises prevailing practice).
There may be a case in future for including the following provisions in the BCA:
10. Minimum energy efficiency levels for pump-units, that may be higher than the
general MEPS levels adopted for those products. This should be considered
once mandatory energy labelling and MEPS is implemented for pump-units, and
sufficient information is collected on the sales-weighted energy-efficiency of
pump-units installed in new pools;
11. Minimum energy efficiency levels for gas pool heaters, that may be higher than
the general MEPS levels adopted for those products. This should be considered
once mandatory energy labelling and MEPS is implemented for gas pool
heaters, and sufficient information is collected on the energy-efficiency of pool
heaters units installed in new pools;
12. Requirements for pump-unit configurations and control strategies to limit power
and rates of flow and to prevent the installation of over-sized filtration pumps
which would operate at low efficiency much of the time (as in California).
These issues should be reviewed from time to time as information accumulates.
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3. Shared and Public Pools
3.1 Type and number of pools
Shared pools are privately owned pools which can be used by any authorised person (as
distinct from domestic pools which are owned by individual households). Typical
examples are swimming pools in the common areas of apartment buildings or hotels,
where the condition of use may be tenancy of an apartment or being a guest at the hotel.
Public pools are open to all users. They are often owned and operated by local
government (although leasing to managing agents is becoming more common). Pools
in this category may range from single unheated outdoor swimming pools to multiple
Olympic standard pools enclosed within large buildings, or aquatic centres.
As public pools are often used for organised or school sporting events they are oftenconfigured as full-length (50m) or half length (25m). A full size Olympic swimming
pool is exactly 50m long, 25m wide and at least 2m deep, giving it a water volume of at
least 2,500,000 litres, or 50 times the volume of the average domestic pool. However,
many public 50m pools are narrower typically 16 to 20m.
The ABS does not appear to have any data on the number of shared or public pools in
Australia. Sydney Water (2005) estimates that there are about 100 public swimming
centres in the Great Sydney area, apart from pools in hotels, clubs, fitness centres or
apartment buildings. Given that Sydney has about 20% of the national population, this
would indicate about 500 public pool nationally. However, many smaller centres would
have a pool, so the number of pools per person outside the capital cities would be muchhigher. At a rough guess there could be 1,000 to 1,500 public pool complexes in
Australia, many with more than one swimming pool.
In 2008 there were 6,200 hotels, motels and serviced apartments with 5 or more rooms
in Australia (ABS 8635.0). If say half of these had a pool that would be 3,000 pools.
There are no direct data on the number of apartment buildings, let alone the proportion
of those with a swimming pool. However, the Census reports the number of apartments
located in buildings of 1 to 2 stories, 3 stories and 4 or more stories. Assuming an
average of 10, 30 and 60 dwellings respectively for each of the above building types
would indicate about 60,000 apartment buildings of 1 to 2 stories, 10,000 of 3 storeys
and over 5,000 of 4 or more storeys. If, say, 1 in 3 of the high rise apartments and 1 in
20 of the rest had pools, that would be another 5,000 pools..
With clubs, fitness centres etc there could possibly be a total of 8,000 to 10,000 shared
swimming pools in Australia.
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3.2 Energy and Water Impacts
Shared and public pools use energy for the same main purposes as domestic pools:
water filtration, sanitisation and heating. However, the amount of energy used per pool
is much higher because average water volume is higher, bather loads are high and the
sanitisation standards for public pools have to meet public health regulations.
For example, shared and public pools are all covered by the Public Health (Swimming
Pools and Spa Pools) Regulation 2000under theNSW Public Health Act 1991, which
states that:
The occupier of a swimming pool or spa pool to which this Regulation applies
must not allow a person to use the water in the pool unless the water in the pool
is disinfected in such a way as to prevent the transmission of scheduled medical
conditions to the other users of the pool.
The Guidelines issued by the NSW Department of Health state that:
all treated water public swimming pools and public spa pools shall be equipped
with an effective water circulation system, filter and continuous disinfectant
dosing control system. Continuous dosing means the use of a metering device to
feed a chemical at a relatively constant rate (NSW Health 2006).6
The Guidelines also specify the periods in which the entire water volume must be
turned over. In effect public and shared pools need to be sanitised and filtered
continuously while open to the public, as distinct from domestic pools, where filters and
sanitisers only need to operate 15% to 25% of the time, even in the swimming season.
Public pools are also far more energy intensive than domestic pools in that most are
heated, many are within buildings which need heating, ventilation and air conditioning,
and many have user amenities with their own energy and water requirements.
The energy and water use of public and shared swimming pools is a matter of
considerable interest to their owners, because the operating costs and utility charges can
be very high. However, comparisons are difficult to make, because almost every study
reports different measures and benchmarks. Some report energy for the entire
swimming centre including amenities and non-swimmer areas, some for the pool hall
only, some for the pool only (with pumping energy and water heating energy sometimescombined and sometimes separately reported).
Table 1 summarises the energy use guidelines from a UK publication (for an entire
aquatic centre ). As the water temperatures are much the same in all public pools, and
the HVAC requirements are driven more from the need to manage condensation from
the pool rather than by external temperature conditions, the energy use of a similar
indoor pool in Australia should be roughly similar.
6The Regulations state that: It is a defence to a prosecution for an offence against this Regulation if the
defendant satisfies the court that the act or omission constituting the offence was done in compliance with
the Guidelines for Disinfecting Public Swimming Pools and Spa Poolspublished by the Department ofHealth as in force from time to time.
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Table 1 Energy budget and energy saving options for a typical small public indoor
aquatic centre
Electricity
kWh/m
2
Heating
kWh/m
2
Total
kWh/m
2
Share of
saving
kWh/yr
(a)Typical pool
Good practice
237
152
1336
573
1573
725
1494350
688750
Potential saving 36% 57% 54%
Better building insulation
Better ventilation management
Improved pool pumps
Regular use of pool cover
Improved Lighting
Operation & scheduling changes
0
-25
-29
-8
-16
-7
-51
-481
0
-145
0
-86
-51
-506
-29
-153
-16
-93
6%
60%
3%
18%
2%
11%
-48450
-480700
-27550
-145350
-15200
-88350
Total potential energy saving -85 -763 -848 100% -805600
Source: UK Energy Consumption Guide 78 (2001) One heated pool 25x12 m surface (a) Total floor area
of centre is 950 m2.
The information about water and energy use in public pools in Australia is rather
limited, although several studies currently under way should improve this situation
during 2009.7 Information about shared pools in hotels and apartment buildings is even
more limited. EnergyAustralia has reported detailed energy use for two high rise
apartment block with pools and spas in Sydney (Table 2). The total annual energy use
in Building A was about 290,000 kWh/yr, or about 5% of total common area electricity
use and 15% of common area gas use. The total annual energy use in Building B
approached 244,000 kWh/yr, or about 27% of total common area electricity use.
Table 2 Typical energy budget for small public indoor pool centre
Electricity
kWh/yr
Gas heating
kWh/yr
Total
Building A Swimming pool
Sauna
Spa
50000
2778
27778
208333
0
0
258333
2778
27778
Combined 80556 208333 288889
Building B Swimming pool
Spa
122222
102778
0
0
122222
102778
Combined 244444 0 244444
Source: Derived by author from EA (2005)
Where present, pools obviously account for a significant proportion of common area
energy use. According to the Commonwealth Department of Resources, Energy and
7The Sydney City Council is collecting energy and water consumption data for all of its aquatic centres;this should be available in March 2009 (personal communication, January 2009). Sydney Water has
commissioned 11 energy and water audits of aquatic centres (The Conserver, October 2009) and is usingthe data to compile benchmarking Guidelines, to be published in mid 2009 (personal communication,
January 2009). The Victorian Aquatic Industries Council has a grant from the Smart Water Fund to carryout a study of water (but not energy) use in 75 aquatic centres in Victoria. The results should be availableduring 2009 (personal communication, January 2009). .
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Tourism Energy Best Practice program, pool energy accounts for between 4% and 8%
of total energy use in hotels.8
3.3 Elements of energy use
In general, the same energy and water uses are present use in public pools and the
buildings which house them as for domestic pools, but on a much larger scale and
designed for high intensity of use.
There are however several important differences in design approach:
Public pool design tends to involve engineers, architects and other buildingprofessionals, whereas domestic pools tend to be designed by builder-packagers;
Many clients commissioning public pools are well aware of the high operating costs,and will instruct designers accordingly, whereas very few domestic pool clients are
aware of this;
Public pools must meet a range of stringent and regularly enforced health standards,some of which are quite prescriptive in terms of sanitisation and water turnover,
whereas the standards for domestic pools are in effect advisory and not enforceable;
Many public pools are housed in buildings, or parts of buildings, which have highservice requirements and energy use of their own and interact with the general
building services in complex ways (some of which offer opportunities, eg use of
waste heat). Very few domestic pools are in this situation.
Pool water management and conditioning
Public pools have much larger pumps than domestic pools. The Australian Standard for
energy efficiency of swimming pool pumps applies to all single phase pump-units
intended to be used in the operation of swimming pools and spa pools, but it will not
cover the 3-phase pumps-units, which tend to be used in public pools. However, the 3-
phase electric motors themselves are subject to MEPS.
Most public pools are heated to between 26C and 28C. Public spas are limited to no
higher than 38C. This increases the rate of both water and heat loss due to
evaporation.
Unlike domestic pools, where the management objective is to lose as little water as
possible in normal use, public pools have to add new water continually: the current
benchmark is about 40 to 60 litres per visitor per day (Sydney Water 2008).
http://www.ret.gov.au/energy/Documents/best%20practice%20guides/energy_case_studies_rydgescapitalhill.pdfand other case studies.
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Heating and Ventilation of Pool Buildings
According to the UK Carbon Trust (2008), the control of evaporation from the water is
a function not normally encountered in standard heating, ventilation and air
conditioning (HVAC) systems, and can therefore be misunderstood by designers and
operators.
The ventilation system is normally the primary (or only) means of:
Controlling the pool hall air quality, temperature and humidity so as to reduceevaporation from the pool and prevent condensation (and, potentially, corrosion
damage).
Maintaining comfortable environmental conditions for different occupants. Removing chlorine and other contaminants from the air.In colder climates, a large amount of useful heat is lost by ventilation of the pool
enclosure, and recovery of that heat is often a priority. In Australia however, heat loss
through ventilation may be necessary to cool the pool enclosure, so high air change
rates may be an advantage rather than a liability, at least for parts of the year. It also
means that exhaust air, even though typically 1C higher than the pool water
temperature, may still be cooler than the outside air, so the heat exchange may need to
work in the opposite direction (ie to cool rather than heat incoming air).
User amenities
Almost all public pools have locker rooms, toilets and showers for bathers. These can
have significant HVAC, lighting and hot water demands of their own. There may also
be administration areas and (less service-intensive) circulation areas, storage and plant
rooms. Public pools may also have adjacent gym areas or other indoor sports courts,
public sitting areas, spectator areas and kitchen and catering facilities. To the extent
that these spaces and functions are all adequately covered by provisions in the BCA,
there are no special requirements when integrated with or attached to public pools.
However, the design of a multi-function building which includes a pool can give rise to
complex interactions of services which can present both problems and positive designopportunities with regard to energy and water management.
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3.4 Potential Role for BCA
There is a case for including the following provisions in the BCA at the earliest
opportunity (subject to formal cost-benefit analysis):
13. Definition of a distinct class of non-domestic swimming pools and spa pools
that correspond to the definition of public pools used in health regulations, eg
swimming pools and spa pools to which the public is admitted, whether free of
charge, on payment of a fee or otherwise, including swimming pools and spa
pools:
(a) to which the public is admitted as an entitlement of membership of a
club, or
(b) provided at a workplace for the use of employees, or
(c) provided at a hotel, motel or guest house or at holiday units, or similar
facility, for the use of guests, or
(d) provided at a school or hospital,
but not including swimming pools or spa pools in private residential
premises.
14. Prohibition of the use of electric resistance water heaters for public swimming
pools or spa pools. The alternatives would include solar (unboosted, electric-
boosted or gas-boosted), gas, heat pump or waste heat;
15. A requirement that all public spa pools be fitted with insulating covers and havea minimum level of thermal insulation;
16. A requirement that all public swimming pools equipped with heating (of any
type) be fitted with a removable pool cover, whether the pool is indoors or
outdoors;
As nearly all public pools would have special design requirements which are likely to
involve engineers or other specialists, general design provisions relating to pipe sizes or
controls which are appropriate for domestic pools are not appropriate for public pools.
There are at present no general Australian energy or water performance standards forpublic pools, for buildings housing public pools (eg Class 9) or the parts of buildings
housing public pools (eg parts of Class 2 or 3). There are several projects under way to
gather data on which such performance standards could be based.
Even if performance standards were developed, it would also be necessary to develop
methods of predicting performance so that compliance with those standards could be
established. It may then also be possible to establish deemed to satisfy provisions: eg
the recovery of heat from moist are ventilated from the pool hall.
There may be a case for including such provisions in the BCA in future, and these
issues should be reviewed from time to time as information accumulates.
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4. Fixed Electric Resistance Space Heating
4.1 Types of Fixed Electric Resistance Heating
Electric resistance heating is currently the most greenhouse gas-intensive means of
space and water heating, even though it is close to 100% efficient at the point of
conversion. This is because the great majority of electricity generated in Australia is
from the combustion of coal, leading to high emissions and low conversion efficiency at
the power stations. Despite the CPRS, the average emissions intensity of electricity
supplied in Australia is still projected to be about 75% of todays levels by 2030
(Treasury 2008).
Table 3 illustrates the typical emissions per unit of useful energy output from the most
common means of space heating. Although natural gas and LPG combustion is less
efficient than electricity at the point of use, the greenhouse gas-intensity is so muchlower that it still has a greenhouse advantage. The use of heat pump technology brings
the greenhouse intensity of electric heating much closer to that of gas or LPG.
Table 3 Typical emissions per unit of heat output, space heating
Typical
efficiency
kg CO2-e/GJ
delivered(a)
kg CO2-e/GJ
useful energy
Electric Resistance
Electric Heat Pump
Natural Gas combustion
LPG combustion
Wood (controlled combustion)
100%
280%
75%
75%
60%
278
278
64
67
14(b)
278
99
85
89
23
(a) Typical full fuel cycle emissions factors for energy delivered and converted. (b) CO2from renewablefuels not counted only CH4and N2O emissions.
There are many possible applications of electric resistance heating in buildings. This
paper is only concerned with electric resistance heaters intended to maintain a
comfortable thermal environment for the occupants of a Class 1 or buildings (or the
residential parts of other building classes), as distinct from:
electric resistance water heaters, which may eventually be covered in other parts ofthe BCA; and
specialised electric resistance heaters designed for non-residential applications, suchas providing local heating for workers within otherwise unheated industrial spaces
(industrial heaters), or blowing warm air across open doorways to prevent leakage
of conditioned air in retail buildings (air curtains).
The definition may need to be further limited to cover stand-alone devices which rely on
electric resistance alone, rather than where electric resistance is used in association with
heat pump technology (eg as booster elements) or with other fuels (eg dual-energy gas
and electric heaters), or as spot reheaters in air conditioning ducts.
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Electric resistance heaters have the advantage of flexibility of location, since no pipes or
flues are necessary. The main disadvantages are high running costs and high
greenhouse gas-intensity. Electricity prices are expected to increase more than other
energy forms as the CPRS begins to influence the energy market, so the running cost
disadvantages will increase.
Electric heaters up to 2.4 kW output can be plugged into a power-point, whether or not
the heater is fixed to the structure or portable. Larger capacity units need fixed wiring,
so need to be installed by a qualified person. The effectiveness of BCA coverage of
plug-in fixed electric heaters is likely to limited, because any provisions can be easily
circumvented (either by the builder or the occupant) by fixing the heaters after
completion and plugging them in to power points pre-positioned for that purpose.
The relatively low capital cost of fixed plug-in electric resistance heating can make it
attractive to project home builders. An even cheaper option is to provide no fixed
heating at all, and let the eventual occupants install portable electric heaters, or any
other type, at their own cost. This is common practice in NSW and Queensland, but isnot generally acceptable to home buyers in the States where natural gas heating is
popular (Figure 5).9
Alternatively, buildings in warmer areas may be equipped with air conditioning, which
will almost always have a reverse cycle heat pump heating capability (cooling-only air
conditioners have disappeared from the market). While this is a relatively efficient form
of electric heating, it comes at the cost of introducing cooling, which may be otherwise
unnecessary and which may contribute to summer peak demand on the supply system.
Homeswith
thisformofmainheating
100.0%
90.0%
80.0%
70.0%
60.0%
50.0%
40.0%
30.0%
20.0%
10.0%
0.0%
NSW Vic Qld SA WA Tas NT ACT Aust
Other
Wood
Gas
Electric - heat pump
Electric - nond ucted
Electric - slab
Electric - ducted
Figure 5 Types of main heating in Australian homes, 2008
9note that most nearly all gas heaters in the NT would be LPG).
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The proportion of existing dwellings and other buildings with fixed electric resistance
heating is not known. Of the main heater types which the ABS surveys (ABS 4602.0)
only electric slab heating and electric ducted heating are definitely fixed and
resistive. Together they account for less than 4% of main heaters. The non-ducted
electric heater category is resistive, but not necessarily fixed. In fact, the great majority
of non-ducted electric heaters in NSW and Queensland are portable, because therelatively low demand for heating in most parts of those States means that multiple
plug-in heaters are adequate. Only in Tasmania and the ACT is it likely that a
significant proportion of non-ducted electric main heating is fixed and hard-wired.
Whatever the form of main heating, many homes will use electric resistance heaters for
secondary heating. For example, a household with an open plan living area served by
a gas or wood space heater will often use electric resistance secondary heaters in
bedrooms and bathrooms. As secondary heaters tend to be 2.4 kW or less, they can
usually be plugged into a standard power-point, whether or not they are physically fixed
to a wall. In fact, some manufacturers offer the same heater bodies in fixed or portable
configurations.
Electric resistance heaters can be broadly classified into three main categories:
Space heaters: these are intended to circulate heated air evenly throughout a space,often in living areas, where higher temperatures are usually desired. They generally
incorporate a forced convection fan as well as the resistance elements;
Background heaters: these rely on natural convection or conduction (contact withthe heated surface, especially floors) to provide background heat in circulation
spaces such as passageways or in bedrooms, where lower temperatures are usually
required than in living areas;
Specialised or local heaters, eg heated towel rails, downward-pointing fan heatersdesigned for bathrooms, or radiant heaters which are intended to heat only the
persons within range of the heater.
Table 4 gives some examples of each type.
Underfloor (slab) heating
Embedding heating systems in the floor is common in cold countries, where homes areheated more or less continuously over the winter, but less common in Australia.
Nevertheless, the local market offers several electric resistance heating systems
designed for embedding in concrete floor slabs, or in the grout layer between the slab
and floor tiles (or under timber, carpet or other surface finish). As the heated air rises
and circulates through the room by natural convection, no other form of heating is
necessary.
The typical installed power density of heating elements is about 100-120 W/m2in living
areas and bedrooms, and 150-200 W/m2in bathrooms, swimming pool surrounds or
other places where people walk barefoot. A typical 4m x 5m living area would have a
total embedded wattage of 2.4 kW, comparable to typical fan or column heater.
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Depending on the heat loss from the space, the average operating power usually falls to
a third to a half of the maximum power, once the slab is fully heated.
Slab-embedded heaters can operate as storage heaters, taking power during parts of the
day or night when electricity is cheaper, and gradually releasing the stored heat at other
times. Under-tile heaters operate more like day-rate space heaters, because the intervalbefore heat is transferred to the space is much shorter. Underfloor heaters in bathrooms
are typically controlled by time clocks to match the most intensive periods of daily use.
All modern electric slab heaters have thermostats, so the power can be regulated or
switched once the space reaches a preset temperature. Larger installations also tend to
be zoned, so rarely occupied rooms need not be continuously heated.
Hydronic heating, in which the heating medium is circulating water or other fluid, may
also be use for underfloor or in-slab installation. The heat source may be any
combustion heater (gas, LPG or wood ) or even an electric resistance water heater, and
any of these may be combined with a solar pre-heater. Various configurations arepossible the heater may serve the underfloor system only, or domestic water heating
and possibly convection air heating as well. Hydronic systems are more complex and
expensive to install and maintain than electric slab heaters, but they may cost less to
operate. However, accurate temperature control and zoning may be more difficult for a
hydronic than an electric resistance system, so a poorly designed and controlled
hydronic system may not have much running cost or greenhouse advantage over a well
designed electric resistance system.
Heat banks
Heat banks work in much the same way as under-slab electric resistance heaters, but
instead of the floor slab the thermal store consists of bricks purpose-made to have a high
thermal storage capacity. These are surrounded by insulation and contained in a metal
cabinet which is usually placed on the floor in the space to be heated (wall fixing to
masonry is possible, but the cabinet can weigh 100-200 kg).
The heater operates as a combined background and convection space heater. The
main difference from other electric heaters is that the heat bank heats the thermal store
at times of low electricity price and then releases the stored heat gradually into the
space. The rate of release is determined by the temperature differential between the
heat store and the air outside the cabinet, and the insulation value of the thermal store.
The main weakness of the design is limited controllability. It is difficult for the user (or
the controls) to project the heat requirement ahead of time, so there is a risk that a fully
charged heat bank will release too much heat the next day, or conversely if the recharge
was partial there will not be enough heat. This can be addressed by having
supplementary booster elements (possibly with the electricity charged at day rate) to
top up heat, by controlling the rate of heat transfer through the operation of fans or
baffles in the insulation, or both. However, it is not possible for a heat bank to respond
to room conditions as directly as a simple on-demand thermostat-controlled electric
heater. At worst, if there is an unexpected warm day in winter, the room windows will
have to be opened to let out the unwanted heat.
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The main advantage of a heat bank compared with conventional electric resistance
space heating is the running cost. Heat banks are in many ways a legacy of older utility
pricing strategies to develop timer-controlled off-peak loads, sometimes as a counter
to the spread of natural gas heating. It is likely that these strategies will increasingly be
replaced by time of use metering and dynamic pricing. This should increase the average
electricity price to heat banks (and possibly reduce the average price to on-demandelectric heaters), so at some point the running cost saving may no longer compensate for
the extra capital costs and lower controllability. However, heat banks and other heat
storages will still be of value to utilities, especially as the share of variable renewable
energy sources in the generation mix increases.
4.3 Potential Role for BCA
Table 4 summarises the configurations and functions of domestic electric resistance
heating discussed above. The shaded areas indicate where coverage by the BCA may
be a practical option.
Table 4 Types of electric resistance heaters and potential for BCA coverage
Heating function Plug-in examples Hard-wired examples
Fixed Background Fixed Panel heaters Underfloor slab heating
Space Fixed convectors Heat banks, convectors
Local/specialised Radiant bathroom heaters Towel-rail heaters (a)
Portable Background Oil-filled column heaters NA
Space Fan heaters NA
Local/specialised Radiant NAShaded area indicates potential for coverage by BCA (a) There are also plug-in fixed towel rails.
There is little point in the BCA covering fixed heaters of 2.4 kW or less, since these
are no more part of the building fabric than a shelf or a toilet roll holder. If the BCA
were to prohibit plug-in fixed electric resistance heaters, say, homeowners (or builders
or tradespersons) would simply fix them after the certified completion of the building
and plug them in to the power points pre-positioned for that purpose. .
The only types of electric resistance heater that could be effectively covered are:
Heaters which are part of the building fabric, eg physically integrated into the floor,wall or ceiling, rather than fixed to their surface; and/or
Hard-wired heaters, which may not be connected to the electricity supply by astandard power point, because they draw more than 10 amps, and/or require a 3-
phase supply, or for safety reasons.
These definition would cover electric slab and underfloor heating, and heat banks, both
of which are relatively rare in existing buildings, and probably even more so in new
ones. Given the small proportion of electric resistance heater uses where BCA coverage
may be practical, is there a rationale for coverage?
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It has been suggested that if electric storage water heaters are excluded from new
dwellings on the grounds of greenhouse gas-intensity, then so should electric storage
space heaters. This does not necessarily follow.
Water heaters deliver a highly standardised service (hot water) so qualitative differences
between types and energy forms are small. There is no way to distinguish water heatedby electricity, gas or solar, so long as it meets the same criteria of availability,
temperature and rate of flow, so the real differences between options are capital cost and
running cost, which in turn reflects greenhouse gas-intensity. As users have no strong