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PART 10: ENERGY EFFICIENCY AND SUSTAINABILITY
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TABLE OF CONTENTS
10.1 Scope … 3
10.1.1 Application of section … 3
10.1.2 Performance requirements … 3
10.1.3 Standards and guidelines … 3
10.2 Mechanical ventilation systems … 3
10.2.1 General requirements … 3
10.3 Refrigeration Equipment … 4
10.4 Hot Water … 4
10.4.1 Need for hot water systems … 4
10.4.2 Fuel source … 5
10.4.3 Solar heating … 5
10.4.4 Standby losses … 5
10.4.5 Storage capacity … 6
10.4.6 Circulating systems … 6
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10.1 SCOPE
10.1.1 Application of Part
This Part sets out requirements and recommendations for energy efficiency in respect of mechanical ventilation on air‐conditioning, lighting, electrical appliances, hot water systems, and other services and equipment installed in buildings.
10.1.2 Performance Requirements
Services and equipment in buildings shall be as energy efficient as practicable and facilitate the conservation of energy.
Note: Requirements and recommendations for thermal insulation are specified in Section 10.4.5.
10.1.3 Standards and guidelines
The following standards and guidelines are relevant to the provisions of this Part:
‐ International Energy Conservation Code, 2003. ‐ Efficiency Standards for Residential and Non‐Residential buildings (2008) ‐ California
Energy Commission. ‐ Draft Ghana Building Code Part 9.3 – Air‐conditioning, Heating and Mechanical
Ventilation.
10.2 MECHANCIAL VENTILATION SYSTEMS
10.2.1 General requirements
Air‐conditioning by means of mechanical refrigeration shall be installed only where absolutely necessary for human comfort, the storage of temperature‐sensitive materials, or the operation of temperature or humidity sensitive equipment or processes.
Notes 1 Spaces which require continuous air change to remove build‐up of smoke, heat, dust or odours from cooking, manufacturing, office machines, etc. should not be air‐conditioned but should be cooled via natural or forced ventilation without the use of mechanical refrigeration.
2 Toilet rooms or other naturally ventilated spaces should be located where possible on exterior walls of buildings, provided with natural or forced exhaust ventilation, and isolated from air‐conditioned spaces by self‐closing, tight fitting doors.
3 Air‐conditioning should not be considered where natural air movement or forced ventilation will meet environmental needs. Natural ventilation through properly located and designed windows and wall openings, or the use of fans or other air‐moving devices, should always be fully considered prior to the
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specification of air‐conditioning equipment. Note that the energy costs for “fan alone” systems require about 1/10th of the energy of air‐conditioning.
4 Air‐conditioning should not be used in areas which are only transiently occupied, ie. For continuous periods of less than ½ hour at a time, such as storage or records rooms, laboratories, dressing rooms and washrooms.
10.3 REFRIFGERATION EQUIPMENT
(a) Refrigeration equipment shall be sized to meet the maximum anticipated load condition and no more. Unused space in refrigerated equipment results in excessive energy use per unit of product stored.
(b) Refrigeration compressor/condenser units shall be located in a shaded, well ventilated location and protected from any nearby source of materials which would clog the condenser coils.
(c) Water cooled equipment shall be fitted with equipment which removes hardness from condenser water. The owner shall be advised as to the necessary maintenance of the water treatment system.
(d) Defrost times for equipment shall be adjusted on‐site on the basis of operating experience rather than being based solely on manufacturer’s recommendation.
10.4 HOT WATER
10.4.1 Need for hot water systems
Domestic hot water should be installed only where necessary. Consideration should be given to not installing water heating equipment except where required for reasons of health, safety, process requirements, or to meet domestic needs. Generally, hot water is required only in the following areas:
(a) Hotels/Apartments: All rooms, public toilets, staff toilets. Not required in beach toilets or showers or public restrooms except where used by food service staff.
(b) Restaurants: Staff and public toilets, kitchen (c) Office Buildings: Hot water not required for toilets. Use instantaneous heaters at janitors
sinks if warm wash water is required.
(d) Commercial Buildings (i) Without food heating: Hot water not required. Instantaneous heater recommended if hot water installed.
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(ii) With food handling: Instantaneous heater for up to 25 seats. Commercial storage‐type heater for more than 25 seat capacity.
(e) Industrial Buildings (i) Food Processing: Hot water not required except where desired or required by
employees for personal clean‐up.
10.4.2 Fuel source
Solar water heating, recovery of heat rejected from air‐conditioning or refrigeration equipment, or recovery of heat rejected from combustion and other heat sources shall be fully considered for new water heating requirements before specifying conventional water heating equipment.
Notes 1 The engineer or architect should demonstrate that such means are either technically impracticable or financially unreasonable before specifying conventional equipment.
2 Conventional storage‐type electric resistance water heaters of greater than 20 litre capacity should not be installed except where other fuels are not available or where safety, for example in locations where open flames are dangerous, reliability, or precision of temperature control is a concern.
10.4.3 Solar heating
(a) Solar hot water or heat recovery systems should be designed and storage capacity sized to accommodate any substantial hot water demands which occur outside the time that the sun is shining or during the time which het recovery is possible.
(b) Storage should be sized such that the solar or het recovery system is capable of providing at least 70% of the average daily hot water demand.
(c) Pumped circulation systems should be considered for all commercial solar water heating systems except for single family residential uses.
10.4.4 Standby losses
Self contained storage‐type water heaters shall have a standby loss not exceeding the equivalent of 43 Watts per square metre of surface area.
Notes 1 Newly purchased tanks should be of the “Energy Saver” or “energy conserving” type provided by several manufacturers – having at least 65 mm of high density fiberglass or equivalent insulation which allows reduced standby losses. Alternatively, standard type storage heaters should be provided with an insulating shroud of the equivalent of at least 65mm of blanket‐type fiberglass insulation in addition to the standard tank insulation.
2 Storage tanks greater than 450 litres should have an overall shell thermal resistance (“R value”) of at least 1.76m2 k/W.
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10.4.5 Storage capacity
(a) Instantaneous (non‐storage) type water heaters should be used whenever possible, especially where projected use is less than 150 litres/day and peak flows are less than 0.1 litres/sec.
(b) Storage water heaters using any fuel should not be used except where high short term demands exceed the capacity of the largest rapid‐recovery (instantaneous) unit available.
(c) Storage temperature for hot water used for normal domestic purposes should not exceed 500C or 1200F except where storage is undersized due to periodic extraordinary demand or where space is limited for storage tanks.
10.4.6 Circulating systems
(a) Pumped circulating systems shall be employed only where absolutely required, such as in hospitals or large apartment buildings occupied full‐time with round‐the‐clock demands where the economy in terms of reduced water wastage from avoiding long runs waiting for hot water at the tap outweigh the heat losses from piping and pump electricity use resulting from continuous circulation.
(b) All buildings where consumption is merely for periodic and sporadic hand wash or cleanup should utilize instantaneous heaters or small storage tanks at each point of use, rather than a central hot water system.
(c) Temperature: Circulating temperature or the thermostat controlling hot water circulation pump should be set no higher than 500C or 1200F for normal domestic purposes – except where special needs require higher temperatures. Storage tank temperature should not exceed 1300F.
(d) All circulating hot water piping or non‐circulating systems with a demand profile which requires that water be maintained at elevated temperature more than an average 6 hours/day, year round, shall be insulated with at least 20 mm fiberglass insulation or equivalent. Domestic hot water supply piping shall meet the insulation requirements for pipe insulation specifies in 5.503.3.
(e) Timers: Where circulating systems are installed, if usage is nil during a period averaging 10 or more hours per week, a time switch should be installed to automatically stop the circulating pump during that period.
(f) Combustion efficiency: Combustion devices installed to produce hot water for any purpose shall have a rated combustion efficiency of at least 80%.
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Notes 1 Newly installed combustion devices should be operated by the installer under conditions simulating those of actual operation and a combustion analysis, and the device adjusted to demonstrate the actual on‐site steady‐state efficiency of the equipment.
2 Atmospheric natural gas or L.P.G. burners shall be exempt from the combustion analysis requirement, however the installer should ensure that operating pressure and air settings are within the manufacturer’s recommended limits for local conditions.
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