Energy Research Building Code of Australia Vol 1 PDF

8/2/2019 Energy Research Building Code of Australia Vol 1 PDF

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INTERNATIONAL SURVEY OF

BUILDING ENERGY CODES EXECUTIVE SUMMARY

FEASIBILITY STUDY A NATIONAL

APPROACH TO ENERGY EFFICIENCYMEASURES FOR HOUSES EXECUTIVE SUMMARY

IMPACT OF MINIMUM ENERGY

PERFORMANCE REQUIREMENTS FOR

CLASS 1 BUILDINGS IN VICTORIA EXECUTIVE SUMMARY

E N E R G Y R E S E A R C H F O R T H E

B U I L D I N G C O D E O F A U S T R A L I A

The lea d Commonweal th

agency on greenhouse

matters

VOLUME 1


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E N E R G Y R E S E A R C H F O R T H E B U I L D I N G C O D E O F A U S T R A L I A V O L U M E 1

Acknowledgments

The Australian Greenhouse Office wishes to acknowledge

the authors of the reports outlined in these Executive Summaries.

The Office of the Australian Building Codes Board author of the

International Survey of Building Energy Codes.

CSIRO Building, Construction and Engineering author of

Feasibility Study - A National Approach to Energy Efficiency

Measures for Houses.

Energy Efficient Strategies author ofImpact of Minimum Energy

Performance Requirements for Class 1 Buildings in Victoria.

The Australian Greenhouse Office also wishes to acknowledge

the support of the Sustainable Energy Authority of Victoria for

co-funding Impact of Minimum Energy Performance Requirements

for Class 1 Buildings in Victoria.

While every effort has been made to ensure accuracy and

completeness, no guarantee is given, nor responsibility taken by

the Commonwealth for errors or omissions in the reports, and the

Commonwealth does not accept responsibility in respect of any

information or advice given in relation to or as a consequence of

anything contained here.

Design Wingrove Wingrove Design

Photos Courtesy of the Housing Industry Association, Michael Shaw

and Mirvac Lend Lease Village Consortium - Developers of

Newington, the Sydney Olympic Village Background Image:courtesy of Robert Peck von Hartel Trethowan.


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F O R E W O R D

1

The Australian Government recognises that improving the

energy performance of buildings is an important part of the

strategy to reduce our greenhouse gas emissions.

The building and construction industry have reinforced to the

Australian Government the need for uniform national building

regulations to address energy and greenhouse concerns.

In July 2000, the Commonwealth announced that agreement

had been reached to incorporate minimum energy performance

requirements into the Building Code of Australia.

Before the changes can be developed considerableresearch will need to be conducted to ensure that the

building code change is at the cutting edge of worlds

best practice, is economically sound, and will deliver

substantial greenhouse benefits.

The Australian Greenhouse Office is pleased to present

this set of three research papers as an important contribution

to the debate on building code change.

The first research paper examines current international

building energy codes, the second paper considers the

feasibility of climate zone based residential building energy

codes, and the third paper examines the impact of a

current State-based regulation.

I would like to commend the authors of the three research

papers, the Office of the Australian Building Codes Board,

CSIRO Building Construction and Engineering, and Energy

Efficient Strategies, as well as acknowledge the contribution

of the respective Steering Committees representing industry

and government organisations.

I hope that this set of research papers will stimulate informed

discussion about greenhouse issues, and facilitate the timely

development of the Building Code of Australia.

Gwen Andrews Chief Executive

Australian Greenhouse Office

September 2000

E N E R G Y R E S E A R C H F O R T H E B U I L D I N G C O D E O F I N A U S T R A L I A V O L U M E 1


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ISBN 1 876536 50 0

Commonwealth of Australia 2000

This work may be reproduced in whole or part for study or training

purposes subject to the inclusion of an acknowledgment of the

source and no commercial usage or sale. Reproduction for

purposes other than those named above requires the permission of

the Australian Greenhouse Office. Requests and inquiriesconcerning reproduction rights should be addressed to:

The Communication Director

Australian Greenhouse Office

GPO Box 621, Canberra ACT 2601

For additional copies of this document, please contact the

Australian Greenhouse Office Infoline on 1300 130 606.

This publication is also available on the

Internet at the following address:

www.greenhouse.gov.au/energyefficiency/building


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C O N T E N T S

INTERNATIONAL SURVEY OF BUILDING ENERGY CODES, EXECUTIVE SUMMARY 4

BACKGROUND 4

OBJECTIVE 4

REGULATORY APPROACHES 4

TECHNICAL 5

HOUSES 6

COMMERCIAL AND PUBLIC BUILDINGS 7

CONCLUSION 7

FEASIBILITY STUDY A NATIONAL APPROACH TO ENERGY

EFFICIENCY MEASURES IN HOUSES, EXECUTIVE SUMMARY 8

BACKGROUND 8

SCOPE AND OBJECTIVES 8

FEASIBILITY ISSUES 8

FRAMEWORKS FOR DEVELOPING DEEMED-TO-SATISFY PROVISIONS 9

REGULATORY ISSUES 10

RECOMMENDATIONS 10

CONCLUSION 11

IMPACT OF MINIMUM ENERGY PERFORMANCE REQUIREMENTS FOR

CLASS 1 BUILDINGS IN VICTORIA, EXECUTIVE SUMMARY 12

BACKGROUND 12

IMPACT OF ENERGY EFFICIENCY PROVISIONS IN VICTORIA 12

KEY FINDINGS 12

BUILDING TRENDS 1990-1999 14

PROFILE OF RESIDENTIAL BUILDING SECTOR 1990-1999 14

CONCLUSION 15

3



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INTERNATIONAL SURVEY OF BUILDING ENERGY CODES EXECUTIVE SUMMARY

BACKGROUND

International and domestic concern is rising over the effect of

greenhouse gas emissions on climate change. The energy

consumed in buildings is responsible for a significant

proportion of total greenhouse gas emissions.

Improving energy efficiency in buildings is an important part

of Australias program to reduce greenhouse gas emissions.

Regulating energy efficiency through building codes has been

a successful strategy for many countries.

This survey of current Building Energy Codes provides aninsight into the different regulatory provisions applied to

buildings in selected countries. The countries whose energy

provisions were evaluated as part of this study were: Canada;

New Zealand; Singapore; the United Kingdom (UK); and the

United States of America (USA) with particular reference to

California and Hawaii.

These countries were selected because they all have

regulatory frameworks similar to Australia and climate zones

comparable to particular parts of Australia.

The current energy provisions of South Australia, Victoria

and ACT are also analysed.

The building energy codes reviewed contain many similarities.

They all contain prescriptive provisions and several have

some form of performance requirement. For those with a

performance base, the prescriptive provisions, if followed,

achieve compliance with the performance requirements.

It should be emphasised that this is a survey of current

practices. It is known that Canada, the USA and other

countries are moving to performance based building codes

which will mean significant changes that could in turn

affect their energy efficiency provisions. The Kyoto Protocolmay also have prompted countries to commence reviewing

their requirements.

OBJECTIVE

The overseas codes studied have various objectives including

conserving fuel, improving energy efficiency, and/or reducing

greenhouse gas emissions. In Australia, the ACT and Victoria

focus on energy efficiency while South Australia also refers to

reducing greenhouse gas emissions. Most other countries

use energy as the stringency measure for their primary

objective and it is understood that they all have some form

of cost effectiveness.

REGULATORY APPROACHES

Most countries specify one or more regulatory approaches.

Some, like the USA, have two or three methods, with up to

five different procedures within each method. Further, there

are tabulated alternatives or trade-offs within a procedure.

However, all codes provide one or more of the following:

s A performance approach.

s A prescriptive approach with usually a multi-tabular format.

s A trade-off approach which compares a notional buildingcomplying with the prescriptive tables with a proposed

building. The trade-off approach usually trades between

envelope thermal insulation elements. The system of

trade-off may allow trading to take into account heating

and cooling systems.

s An energy rating approach that compares a notional

building to the proposed building on an energy

consumption or cost basis.



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The proposed New Zealand and Canadian codes and current

USA codes, all contain a method of compliance that involves

comparing the proposed building with a similar standard

building that complies with code requirements. The standard

and proposed buildings must have similar features such as

building dimensions, location, fuel sources and type of use.

This allows direct comparison of unique characteristics and

trade-offs between energy saving features. Any assumptions

made in the calculations that may effect the result will be

incorporated into both buildings and so minimise any impact.

This is particularly important when using computer software.

Some codes also have mandatory requirements,

meaning those particular requirements cannot be traded,

while other requirements for the same system can be traded.

Even where trading is permitted there may be a limit on

the extent of that trading.

Other than New Zealand and the UK, the overseas codes

studied are not strictly performance based in the Australian

context. This may partially explain the degree of complexity

in the Canadian and USA codes as they cover equivalence to

Deemed-to-Satisfy Provisions with the trade-off approach, and

allow for options and innovation, all within the prescriptive

code. In Australia, this is done outside the code as an

assessment method.

TECHNICAL

All national codes studied have a geographic basis with

reliance on tables or maps to show values that vary around

the country. These include weather or location specific data,

thermal resistance values and for some, fuel type availability.

Several national codes call up standards for example,

Canada and the USA reference an ASHRAE standard;

the UK references Approved Document L; and the New

Zealand Code references New Zealand Standards.

In all the codes examined, houses and other buildingsare treated separately. All overseas countries have air

tightness requirements with most involving some sealing

treatment for the building envelope for both housing and

other buildings. These include the provision of dampers

in flues, sealing of service penetrations, full caulking of all

building joints, window sealing performance, construction

precautions and on site pressure testing performance.

The USA requires swimming pools and spas to have covers

and has requirements for pumps, heaters and controls.

None of the codes examined has provisions for

embodied energy.

The range of overseas exemptions and limitations are

extensive. They include very small buildings, energy used for

process equipment, farm buildings, holiday houses, buildings

not using much energy, buildings with no heating or cooling

proposed or likely, and certain building systems (emergency

lighting, smoke control etc).



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HOUSES

Most overseas codes examined have a relatively straight

forward national approach for houses. They usually cover

envelope thermal resistance; sealing the envelope; efficiency

of the basic equipment; provision of easily accessible controls,

and; insulation of hot water piping ductwork.

Hawaii and Singapore have specific provisions for highly

ventilated houses and their climates are similar to some

parts of Australia. Further investigation into the effectiveness

of their provisions would be useful if Australia was toconsider similar requirements.

The extent of climatic or geographic zoning usually depends

upon the size of the country or the diversity of its climate.

They range from 38 zones in the USA to one in Singapore.

For the envelope of houses, most overseas codes cover

wall, floor and roof insulation, windows and air leakage.

Some include requirements for window shading, heater

efficiencies, low water flow showerheads and the prohibition

of pilot flames in equipment.

The requirements for windows range from a maximum

window to wall ratio, to more complicated calculations.

No country in the study regulates internal lighting of houses.

Some regulate external lighting to the extent of requiringautomatic or timer actuated switching. Some have

requirements for lighting in common areas of group housing.

For the codes examined, provisions for houses are

summarised in Figure 1.

Performance Space Heating HotCountry v Prescriptive Building Envelope or Cooling Lighting Water Other Exemptions

United Kingdom Performance Minimum R rating Yes No Yes Small extentions


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COMMERCIAL AND PUBLIC BUILDINGS

All overseas codes examined focus on the building

envelope and the main engineering systems including

lighting, air-conditioning, hot water systems, principal

equipment, piping insulation and system controls.

The Canadian and USA codes for public and commercial

buildings have multiple methods, procedures and option

paths, and appear complex. All performance and

prescriptive codes require specialist energy expertise

to use and assess compliance.

Most overseas provisions for envelopes in large buildings

are complex but are considerably simpler for smaller

commercial and public buildings. The prescriptive approach,

in particular, for larger buildings can be very detailed taking

into account thermal resistance of walls, floors, roof and

windows as well as radiant gains through windows and

skylights. The radiant gains mean that shading devices,

fenestration and building orientation become important.

Usually the simplistic approach is based on a specified

maximum window area not being exceeded.

The more complex approach gives a range of options for

the performance of all envelope elements as the windowarea increases.

Although the scope varies, all overseas countries surveyed

have requirements for the air-conditioning systems.

These regulations cover the efficieny and fuel type of

refrigeration and heating equipment, electric motors, pumps

and fans. They also cover isolating and operating controls,

acceptable or prohibited system types, as well as piping

and ductwork insulation.

Most countries require metering to individual residential

units in apartment blocks and to each floor or tenancy in

other buildings. Most also require monitoring or data logging

facilities in commercial and public buildings to assist energy

management and auditing. Hawaii has requirements thatinclude providing access for maintenance and the provision

of manuals.

Some countries have requirements for electric motors

and the avoidance of continually burning pilot flames on

gas equipment.

For the codes examined, provisions for commercial and

public buildings are summerised in Figure 2.

CONCLUSION

The findings of this survey, and the recommendations

contained in the Scoping Study published by the Australian

Greenhouse Office in 1999 provide a strong technical basis

for the development of appropriate energy performance

regulations for Australian buildings.


Performance Space Heating HotCountry v Prescriptive Building Envelope or Cooling Lighting Water Other Exemptions

United Kingdom Performance Minimum R rating Yes Yes Yes Small extentions


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F EAS I B IL I T Y S T U DY A N AT I ON AL AP P ROACH TO EN ERGY EF F I C IEN CY

MEASURES FOR HOUSES EXECUTIVE SUMMARY

BACKGROUND

Reducing the amount of energy used to achieve comfortable

levels of temperature and humidity in buildings is an important

strategy to reduce Australias greenhouse gas emissions.

The Commonwealth, State and Territory Governments have

agreed to incorporate a nationally consistent framework of

minimum energy performance requirements into the Building

Code of Australia (BCA), with the aim of significantly

reducing the greenhouse impact of all new and substantially

refurbished buildings.

SCOPE AND OBJECTIVES

This study assesses the feasibility of incorporating energy

efficiency measures into the national building regulatory

framework for houses. It builds on the Scoping Study of

Minimum Energy Performance Requirements for Incorporation

into the Building Code of Australia, published by the Australian

Greenhouse Office in 1999.

The national vehicle for building regulation is the BCA.

The Housing Provisions cover Class 1 and Class 10 buildings,

which are essentially domestic buildings.

There is a requirement that measures in the BCA be cost-

effective. The diversity of Australian climates means that

the cost benefits of energy efficiency measures will vary

considerably across the country and this must be reflected in

the BCA. These same climatic factors contribute to the variety

of building styles in Australia and the variety of methods used

to achieve thermal comfort. Mindful of these issues, particular

attention has been given in this study to the development of

a structure which may differentiate acceptable construction

practice (called Deemed-to-Satisfy Provisions in the BCA)

according to:

s geographic location; and

s building style (for example, whether the building is

designed for predominant use of natural ventilation

or to be conditioned)

Australian Standard AS 2627.1 provides a structure for

geographic differentiation since it gives recommendations

for wall and ceiling insulation by location. This standard is

not suitable in its present form for referencing by the BCA,

but the possible form and role of its successor is considered

in the study.

This report explores the form and general content of

potentially feasible energy efficiency measures. All of those

presented are hypothetical. No actual measures have been

developed at this stage.

FEASIBILITY ISSUES

Heat flow controls

The types of heat flow that a building must control to be

energy efficient are:

s conductive heat flows through roofs, walls, floors and

windows

s solar heat gains through windows and skylights

s ventilation and infiltration

For each of these, there are measures specific to building

elements which could be regulated by the BCA in order to

control heat flow. These measures include:

s minimum insulation levels for ceilings, walls,

floors and windows

s specified permanent shading of window and walls

s maximum window areas (as a percentage of total

floor area) and shading coefficients for solar gain

s specified opening sizes (as a percentage of total floor

area) and maximum ventilation path lengths to facilitate

natural airflow

s weather stripping and dampers to control infiltration



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Defining climate zones

Dividing Australia into a number of climate zones is a simple

way of devising climate-specific regulations. These zones

would be regions that are climatically sufficiently similar to

justify common energy efficiency measures.

The overall process for establishing suitable climate zones

appears to be feasible. The study found that an important step

is the development of basic zoning methodology or criteria.

The number of zones to be established depends on the

balance between accuracy and simplicity. Given an

expectation of reasonably spaced transitions between

levels of insulation, glazing or other measures, an

appropriate number of zones would be between 6 and 12.

FRAMEWORKS FOR DEVELOPING

DEEMED-TO-SATISFY PROVISIONS

Three approaches have been studied as possible ways

to frame Deemed-to-Satisfy Provisions to meet residential

energy efficiency requirements. These frameworks have

common features. They all presume an Australian climatemap which would have a number of zones that would allow

practical tabulation of measure sets for each zone; they

categorise houses into either low or high ventilation; and

they categorise houses according to their thermal mass and

window size.These choices may have a fundamental influence

on the thermal performance of the house and the relative merits

of measures for insulation and glazing.

Framework A: Elemental requirements

This framework would be based on tables specifying values

for the nine key performance measures for each zone.

These measures are roof, wall and floor insulation, overall

glazing area, window shading, wall shading, ventilation,

infiltration, and other climate specific measures.

Framework B: System performance measures

This framework would be based on system performance

measures. It would replace grouped elemental measures

(such as insulation levels for walls, ceilings and floors) with asingle index that represents a weighted average for individual

component contributions. This system would allow trade-offs

between the measures in each group, providing greater

flexibility for designers and builders.

Framework C: Point-score methods

This framework would be based on a point-scoring system.

Under this system, points could be allocated to each measure

according to its cost-benefit and energy performance value.

Houses would have to achieve a minimum total number of

points to satisfy the energy efficiency requirements.



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Framework comparison

All three frameworks are technically capable of setting

realistic minimum criteria for energy performance for

Australian housing. While frameworks B and C may

provide greater accuracy and flexibility, they require

more calculations and impose some additional complexity

during checking at the building permit/approval stage.

They are therefore not recommended as a framework

for Deemed-to-Satisfy Provisions.

It is recommended that a detailed form of framework A,

incorporating elemental requirements for three levels of

thermal mass and two levels each of ventilation and

glazing, be the starting point for development of

Deemed-to-Satisfy Provisions.

Basis for setting stringency levels

The report found that the stringency levels should be

based in the main on energy or related criteria, such as

greenhouse gas production. In general, the use of comfort

or other non-energy-based criteria is not feasible. However,

comfort-related factors will be involved in assessing the true

energy performance of houses and in the suitability andstringency of different measures in different climates.

REGULATORY ISSUES

When developing new building controls there are three

distinct areas within the Housing Provisions performance

structure that need to be considered.

s clear Performance Requirements

s acceptable Deemed-to-Satisfy Provisions

s methodology for Alternative Solutions

The three areas are an integral part of the Housing

Provisions and work together to provide effective

building controls.

RECOMMENDATIONS

Scope

The energy efficiency measures should apply to all new

Class 1 buildings. For alterations and additions,

the proposed energy efficiency measures should only apply to

the proposed construction works. A guideline for refurbished

buildings should be published for jurisdictions where the

legislation may require the existing Class 1 building to be

upgraded to comply with the new Housing Provisions

Performance Requirements. The general community should

be informed about the benefits of upgrading existing

buildings during the alterations and additions process.

The Housing Provisions should include controls for

services and fixtures that can be approved at building

permit and occupancy approval stage and can be

demonstrated to be a permanent feature or fixture of the

building. The control of fixtures can be implemented as

part of, or as an additional requirement to, the building

envelope requirements. The requirements for services

controlled in the Housing Provisions must be compatible

with other legislative requirements.

Implementation

s The Australian Building Codes Board should form

a committee to advise on the development and

implementation of energy efficiency measures for houses.

s If the energy efficiency measures are determined likely

to have a significant negative impact on current industry

practices, then a staged approach to their introduction

could be considered.


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Education and advice

s An education strategy should be developed and

implemented. The education strategy should be delivered

during the development and implementation of the energy

efficiency measures. The education process should

involve all aspects of the industry and community affected

by the proposed energy efficiency measures. An explanatory

information guide should be developed to accompany

the introduction of energy efficiency measures into the

Housing Provisions.

s Individual jurisdictions or associations should consider the

likely need for advice when measures are introduced and

may wish to provide an energy efficiency measures advisory

service for some 18 months from the implementation of

the energy efficiency measures.

Enforcement

s Special conditions for enforcementare not necessary

provided that: an education strategy has been developed

and implemented; the measures are compatible with

industry practice; and supporting resources are available

during the implementation period.

Future development

s The Australian Building Codes Board and Australian

Greenhouse Office should agree to continue the

development program beyond the initial introduction of

energy efficiency measures.

CONCLUSION

The direction of the Objectives, Functional Statements and

Performance Requirements of the energy efficiency measures

should be determined by the Australian Building Codes Board

in conjunction with the Australian Greenhouse Office as a

matter of priority.

The Performance Requirements should clearly state that the

intent is to minimise greenhouse gas emissions by using

energy efficiently.

To provide information to assist compliance with Deemed-to-Satisfy Provisions it is recommended that the Housing

Provisions contain Acceptable Construction Practice and

reference Acceptable Construction Manual(s).

The development of the Acceptable Construction Manual(s)

should be managed so that they are available when the energy

efficiency measures are introduced.

To assist verification of Alternative Solutions, the following

processes should be considered: development of assessment

methods; publication of a guideline document to assist in

the use of assessment methods, and development of an

education module and implementation of training on the use

of Alternative Solutions.



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BACKGROUND

Following studies during the 1980s, regulations for the

insulation of new dwellings came into force in Victoria

under the Building Control Act (Vic) on 18 March 1991.

These regulations were replaced by similar provisions for

Class 1 buildings in the Victoria Additions of the Building

Code of Australia 1996 Volume Two (BCA96).

To meet the objective of efficient use of energy for internal

heating and cooling, when seeking building approval it

must be demonstrated that the building either:

s Complies with specified minimum R values of insulation

for roof or ceiling, external walls and ground floor

(Deemed-to-Satisfy Provisions), or

s Achieves a House Energy Rating of at least 3 star

using a nominated software tool.

In practice, almost all residential building approvals in

Victoria have been based on compliance with minimum

insulation requirements.

IMPACT OF ENERGY EFFICIENCY

PROVISIONS IN VICTORIA

The National Greenhouse Strategycalls for energy efficiency

standards for residential and commercial buildings to be

implemented by mandatory standards through amendment

of the Building Code of Australia.

To help build a better understanding of the effectiveness

of Building Energy Codes, the Australian Greenhouse

Office and the Sustainable Energy Authority of Victoria,

in co-operation with the building industry, the Australian

Building Codes Board and Local Government in Victoria,

examined the impact of current mandatory energy

efficiency measures for houses in Victoria.

Methodology

In the study, energy consumption and greenhouse gas (GHG)

emission estimates were based on the thermal efficiency

of a representative sample of Class 1 buildings built in

1990 (pre-regulation) compared with a sample of similar

buildings built in 1999.

The study examined 110 council approved house plans

from 1990 and 240 plans from 1999. The houses were

screened to make sure they were representative of the

total building activity in Victoria.

The House Energy Rating software tool used for analysis

was FirstRate, a member of the NatHERS family of energy

modelling tools, developed by the Sustainable Energy

Authority of Victoria.

Apart from the business-as-usual scenario (with regulations

in place from 1991), the study also modelled alternative

thermal performance scenarios of the building shell for

comparative evaluations.

KEY FINDINGS

The study estimated that both heating and cooling energy

consumption and GHG were 9% less per annum by year

2000 than would have been the case if the minimum energy

performance requirements of the building regulations had

not been introduced.

Figure 3: Comparative estimates for statewide energyconsumption and GHG emissions, per annum

Case Energy GHGstudy consumption emissions

1990 before regulations 59.0 PJ 4.0 Mt CO2-e

2000 without regulations 82.6 PJ 5.5 Mt CO2-e

2000 with regulations 75.0 PJ 5.0 Mt CO2-e

2000 savings 9% 9%

PJ (Peta Joules = 1015

Joules)

Mt CO2-e (million tonnes of carbon dioxide equivalent)

IMPACT OF MINIMUM ENERGY PERFORMANCE REQUIREMENTS FOR

CLASS 1 BUILDINGS IN VICTORIA EXECUTIVE SUMMARY



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Three alternative cases were modelled for GHG emissions

for statewide heating and cooling across the period 1990

to 2000 for the total residential building stock. These case

studies assumed thermal performance equivalent to an

average performance standard of NatHERS 1, 3 and 5 stars

ratings, instead of the current legislation.

This modelling has established that without regulations,

houses built between 1990 and 2000 would have had

an average thermal performance equivalent to less than

NatHERS 1 star rating. With current regulations, the post

1991 housing stock was found to have an average

performance level of 2.2 stars.

Looking solely at houses built after March 1991 (ie those

subject to energy efficiency regulations), the study modelled

GHG emissions for heating and cooling for a range of thermal

performance standards. The findings are compared with the

actual performance standard set in the 1991 regulations.

Figure 4: GHG emissions of buildings for

various thermal insulation scenarios in 1999

Case % Change instudy GHG emissions

5 star rating 31 reduction


Higher insulation + double glazing (low -e) 21 reducti on


Regulations + double glazing (low-e) 14 reduction

Higher insulation 7 reduction

With 1991 regulations base line 0

2 star rating 3 increase

No regulations + double glazing (low-e) 22 increase

1 star rating 27 increase

No regulations 36 increase

Distribution of efficiency

Despite the introduction of mandatory minimum insulation

requirements, the 1999 sample showed that a substantial

number of poorly performing houses were produced.

Across the total 1999 housing sample, more than 80 percent

failed to meet the 3 star performance requirement, with some

only achieving 1 star or less. It appears that many cost-

effective opportunities for energy saving have been missed.

Figure 5: Thermal Efficiency DistributionBy Star Rating of the 1999 Sample Housing


0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

No.

ofDwellings(19

99)

Star Rating

0

10

20

30

40

50

60

70

80

90

100

110

120

Shepparton

Ballarat

Melbourne


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BUILDING TRENDS 1990-1999

Analysis was also conducted to identify the impacts of the

insulation regulations and to highlight trends that have been

occurring since regulations were introduced.

Thermal efficiency

Improvements in average thermal efficiency since

the introduction of regulations have been modest:

s Since 1991-1992 there has been a total of only

6% improvement in building shell thermal efficiency(in terms of energy per unit of floor area).

s This weak trend has levelled off to practically

zero over the last few years of the study.

s Due to the increasing average floor area per house,

total energy consumption per house has actually

increased significantly over the period.

Apart from improvements gained as a result of mandatory

insulation regulations, improvements in building shell

thermal efficiency in other areas of building design are

almost non-existent.

Application of solar passive design principles

Based on criteria established in the report for assessing

solar passive design, only 7 houses out of the 240 sampled

in 1999 were found to meet the criteria. This is considered

representative of current building practice in Victoria.

This demonstrates that passive solar design practices

are not applied to any significant extent in Victoria by the

building industry.

PROFILE OF RESIDENTIAL BUILDING

SECTOR 1990-1999

Since the introduction of energy efficiency legislation in 1991,

it is estimated that 226,000 new Class 1 buildings have been

added to the Victorian housing stock, comprising 200,000

detached dwellings and 26,000 attached dwellings.

A number of factors unrelated to the 1991 regulations have

contributed to improving the overall thermal performance of

Victorian housing.

Increase in average floor area

Average floor areas of detached housing from 1990 to 1999

has risen by 43m2

or 25%. Average floor areas for detached

housing has risen by 35m2

or 31%. Increased floor area is

usually associated with an increase in the floor area to wall

area ratio.

Analysis of the samples show that the floor area to wall

area ratio has increased by approximately 10% between

1990 and 1999. Such an increase will in itself improve the

thermal efficiency of the house, all other things being equal.

Housing types

Over the study period, there has been a general trend

towards an increase in the proportion of attached housing

in the building stock in terms of total floor area - from 4%

in 1990 to 9% in 1999.

The average thermal efficiency of attached housing in the

sample was found to be 11% better than for detached

housing. The increase in the proportion of attached

housing is estimated to account for about 0.6% of the overall

improvement in thermal efficiency of housing built since 1991.


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Floors

Over the study period, the use of concrete slab-on-ground

floors increased by 5% at the expense of timber construction.

The study also shows that the thermal performance of

buildings with concrete floors in the sample is 14% better

than for suspended timber floors.

Whilst other factors apart from greater use of concrete floors

may be driving this improvement, this trend is estimated to

account for a 0.7% improvement in thermal efficiency of the

housing stock since the introduction of the 1991 energy

efficiency legislation.

Wall construction

The proportions of each type of wall construction for detached

housing were almost identical in 1999 as they were in 1990.

Brick veneer accounts for about 85% of all construction for

the detached housing market.

Windows

The area of glass per house increased on average by 17%

over the period of the study. At the same time, the average

conditioned floor area increase by 34%. As a result, the

average window to floor area ratio reduced from 31% to 27%.

As the thermal resistance of insulated walls is generally

higher than for currently used glazing, the trend towards

reduced window areas is estimated to account for a small

part of the improvement in thermal efficiency of the post

1991 building stock.

The use of high performance windows continues to be very

limited in Class 1 buildings in Victoria, estimated at less than

2% of the market.

Housing orientation

The 1990 and 1999 housing samples were analysed to

determine the average area of glazing on each facade.

While there is a clear bias for facades to align with the

ordinal points of the compass there is little bias shown

towards the use of windows in any one of these directions.

For the majority of houses in the sample, it appears that

little consideration was given to improving thermal efficiency

through optimisation of glazing on facades with a

northerly aspect.

Housing location

Since the introduction of legislation in 1991 there has been a

5% increase in building activity in the Melbourne climate zone

at the expense of the more severe Ballarat and Bendigo

climate zones. This trend is estimated to account for about

1.8% of the improvement in average thermal efficiency of

houses built since the 1991 legislation.

CONCLUSION

The introduction of thermal performance requirements for

the building shells of Victorian houses have reduced energy

consumption and GHG emissions. Avenues for additional

savings have been identified and quantified in the study but

not costed.

While the present policy of mandatory thermal insulation will

continue to deliver significant savings in energy consumption

and GHG emissions, the policy offers little scope to go beyond

the current practice.

The report finds that while there is overall compliance with

mandatory requirements for thermal performance, it appears

that the residential building industry does not always takeadvantage of simple or low-cost design options for additional

thermal efficiency.

The Deemed-to-Satisfy Provisions of BCA96 have

delivered residential buildings with a state average rating

of NatHERS 2.2 stars, although the performance goal is

3 stars. The insulation component of the Deemed-to-Satisfy

Provisions has also permitted buildings with less than 1 star

rating to be constructed.



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