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Section J Energy Efficiency
JP1
A building, including its services, must have, to the degree necessary, features that facilitate the efficient use of energy appropriate to—
(a)
the function and use of the building and services; and
(b)
the internal environment; and
(c)
the geographic location of the building; and
(d)
the effects of nearby permanent features such as topography, structures and buildings; and
(e)
solar radiation being—
(i)
utilised for heating; and
(ii)
controlled to minimise energy for cooling; and
(f)
the sealing of the building envelope against air leakage; and
(g)
the utilisation of air movement to assist heating and cooling; and
(h)
the energy source of the services.
Efficient use of energy
JP1 refines the intention of JO1 and covers those aspects of the building fabric and services that are to be considered for the building to achieve the required thermal performance. The words “envelope” and “services” are italicised in the text to indicate that they are terms defined in the BCA, specifically for the BCA use and context (the definition may not be appropriate in another context).
‘To the degree necessary’The term “to the degree necessary” has been included because:
- there may be a minimum energy consumption below which it may be unnecessary or impractical to regulate; or
- there may be some building types for which it may be unnecessary or impractical to regulate; or
- some of the features may not be appropriate for some building types.
It may also be inappropriate to require energy efficiency in some instances, for example where there may be a conflict with safety or health requirements.
When considered in conjunction with JP1(h), the term “to the degree necessary” may be used to justify an Performance Solution that utilises renewable energy sources.
‘Facilitate’The term "facilitate" is used in to highlight the need to consider the installation of energy efficiency measures in a building where there is likelihood that an artificial heating or cooling system will be installed in the building irrespective of the initial design.
The term also indicates that energy efficiency is not assured but may only be achieved if the building is operated, managed and maintained correctly.
‘Permanent’In the term ‘permanent’ is used to describe features that will have a long term impact on the building. This includes natural features of the landscape, such as mountains and escarpments, while permanent man made features would include buildings likely to be in place for a long period of time.
'The energy source of the services'JP1(h) permits the energy source of the service to be considered. This means that the net energy obtained for services from renewable energy sources such as solar, geothermal, wind and bio-fuels may be considered as "free” energy in calculating the energy consumption. Similarly, heat reclaimed from another “free” source such as a by-product from co-generation type processes as well as other industrial processes, which would otherwise be rejected from the building could be considered as "free” energy in calculating the energy consumption.
JP2 * * * * *
JP3
Heating such as for a conditioned space must, to the degree necessary, obtain energy from—
(a)
a source that has a greenhouse gas intensity that does not exceed 100 g CO2-e/MJ of thermal energy load; or
(b)
an on-site renewable energy source; or
(c)
another process as reclaimed energy.
JP3 addresses the greenhouse gas pollution potential of the energy source and requires the source to be of a low greenhouse gas intensity such as natural gas or renewable energy sources such as solar, wind or geothermal, in preference to electricity or oil. Accordingly, for the purposes of the BCA, GreenPower is not an on-site renewable energy source.
Reject heat may be from a refrigeration chiller, a co-generation type process, or industrial process equipment.
The intent of JP3 is to constrain the use of a high greenhouse gas intensity source of energy for heating a conditioned space. It does not prevent the use of electricity because the greenhouse gas intensity is related to the thermal load rather than the energy consumption which is covered by JP1. Reasonably efficient electrical heating, such as heat pumps, can lower the effective intensity of the supply source. JP3 also contains the qualification that it is to be applied "to the degree necessary", allowing electricity to be used, even by low efficiency plant when there are no reasonable alternatives.
Note that this requirement only applies to heating and not cooling, lighting or other services which still require electricity.
VERIFICATION METHODS
JV1 * * * * *
JV2 * * * * *
Blank clause
This clause has deliberately been left blank.
The content of , which existed in BCA 2007, has been removed. The Verification number has been retained without text so as not to change the numbering of the current BCA from that of BCA 2007.
JV3 Verification using a reference building
(a)
For a Class 3, 5, 6, 7, 8 or 9 building, compliance with is verified when it is determined that the annual energy consumption of the proposed building with its services is not more than the annual energy consumption of a reference building when—
(i)
the proposed building is modelled with the proposed services; and
(ii)
the proposed building is modelled with the same services as the reference building.
(b)
The annual energy consumption of the proposed building in (a) may be reduced by the amount of energy obtained from—
(i)
an on-site renewable energy source; or
(ii)
another process as reclaimed energy.
(c)
The annual energy consumption calculation method must comply with the ABCB Protocol for Building Energy Analysis Software.
(d)
The annual energy consumption in (a) must be calculated—
(i)
for the reference building, using—
(A)
the Deemed-to-Satisfy Provisions for Parts J1 to J7 but including only the minimum amount of mechanical ventilation required by Part F4; and
(B)
a solar absorptance of 0.6 for external walls and 0.7 for roofs; and
(C)
the maximum illumination power density without any increase for a control device illumination power density adjustment factor; and
(D)
air-conditioning with the conditioned space temperature within the range of 18° CDB to 26° CDB for 98% of the plant operation time; and
(E)
the profiles for occupancy, air-conditioning, lighting and internal heat gains from people, hot meals, appliances, equipment and heated water supply systems—
(aa)
of the actual building—
(AA)
if the operating hours per year are not less than 2 500; or
(BB)
if the daily operating profiles are not listed in ; or
(bb)
of ; and
(F)
infiltration values—
(aa)
for a perimeter zone of depth equal to the floor-to-ceiling height, when pressurising plant is operating, 1.0 air change per hour; and
(bb)
for the whole building, when pressurising plant is not operating, 1.5 air change per hour; and
(ii)
for both the proposed building and the reference building using the same—
(A)
calculation method; and
(B)
location, being either the location where the building is to be constructed if appropriate climatic data is available, or the nearest location with similar climatic conditions, for which climatic data is available; and
(C)
adjacent structures and features; and
(D)
environmental conditions such as ground reflectivity, sky and ground form factors, temperature of external bounding surfaces, air velocities across external surfaces and the like; and
(E)
orientation; and
(F)
building form, including—
(aa)
the roof geometry; and
(bb)
the floor plan; and
(cc)
the number of storeys; and
(dd)
the ground to lowest floor arrangements; and
(ee)
the size and location of glazing; and
(G)
external doors; and
(H)
testing standards including for insulation, glazing, water heater and package air-conditioning equipment; and
(I)
thermal resistance of air films including any adjustment factors, moisture content of materials and the like; and
(J)
dimensions of external, internal and separating walls; and
(K)
surface density of envelope walls over 220 kg/m2; and
(L)
quality of insulation installation; and
(M)
assumptions and means of calculating the temperature difference across air-conditioning zone boundaries; and
(N)
floor coverings and furniture and fittings density; and
(O)
internal shading devices, their colour and their criteria for operation; and
(P)
number, sizes and floors served by lifts and escalators; and
(Q)
range and type of services and energy sources other than energy generated on-site from sources that do not emit greenhouse gases such as solar and wind power; and
(R)
internal artificial lighting levels; and
(S)
internal heat gains including people, lighting, appliances, meals and other electric power loads; and
(T)
air-conditioning system configuration and zones; and
(V)
range of internal temperatures and plant operating times; and
(W)
supply heated water temperature and rate of use; and
(X)
infiltration values unless there are specific additional sealing provisions or pressure testing to be undertaken; and
(Y)
unit capacity and sequencing for water heaters, refrigeration chillers and heat rejection equipment such as cooling towers; and
(Z)
metabolic rate for people; and
(iii)
for the proposed building using a solar absorptance for the roof and walls 0.05 higher than that proposed; and
(e)
Where the annual energy consumption of the heated water supply or the lifts and escalators are the same in the proposed building and the reference building, they may be omitted from the calculation of both the proposed building and the reference building.
(f)
A lift in a building with more than one classification may be proportioned according to the number of storeys of the part for which the annual energy consumption is being calculated.
(g)
The design must include—
(i)
the ability to achieve all the criteria used in the annual energy consumption calculation method such as having an automatic operation controlling device capable of turning lighting, and air-conditioning plant on and off in accordance with the occupancy and operating profiles used; and
(ii)
compliance with—
(A)
for general thermal construction; and
(B)
for compensation for a loss of ceiling insulation; and
(D)
BS 7190 for testing a water heater; and
(E)
AS/NZS 3823.1.2 at test condition T1 for testing package air-conditioning equipment not less than 65 kWr; and
(F)
AHRI 550/590 for testing a refrigeration chiller; and
(G)
for facilities for energy monitoring.
This Verification Method compares the energy consumption of a proposed building to the energy consumption of a reference building based on the Deemed-to-Satisfy Provisions. If the energy consumption of the proposed building does not exceed the energy consumption of the reference building, compliance with is achieved.
Through this modelling process, it must be demonstrated that a Performance Solution is equivalent to, or better than, the Deemed-to-Satisfy Provisions. This equivalency is also one of the Assessment Methods recognised in the BCA.
includes provisions in designed to protect the thermal performance of the building’s envelope from "trading" off its performance.
The steps to using this Verification Method are:
- Determine the annual energy consumption allowance by modelling a reference building, i.e. a Deemed-to-Satisfy complying building based on the criteria in .
- Calculate the theoretical annual energy consumption of the proposed Performance Solution using either the subject building's criteria or that in .
- Calculate the theoretical annual energy consumption of the proposed Performance Solution, with the services modelled as if they were the same as that of the reference building.
- Compare the theoretical annual energy consumption calculated in steps 2 and 3 to the annual energy consumption allowance calculated in step 1 to ensure that in both cases, the annual energy consumption is not more than that allowed.
The same software must be used in all modelling runs.
can be used for all buildings using the occupancy profiles and other assumptions appropriate for the subject building or those provided in .
permits the profiles and internal heat loads of the proposed buildings to be used in the calculations provided the operating hours are not less than 2,500 per year. The profiles and loads of need only be used if the hours of operation are less than 2,500 per year. Alternatively, the profiles and loads of can be used in all cases. The reason for permitting the expected profiles and internal loads of the proposed building to be used is that, provided the numbers of hours of operation are reasonable, different hours and loads have minimal impact on the modelled outcome as the same values must be used in assessing the reference building as well as the proposed building.
requires the Performance Solution to be able to achieve all the criteria used in the annual energy consumption calculation method. This means that the solution must include such features as a time switch that is capable of turning lighting and air-conditioning plant on and off in accordance with the occupancy and operating profiles used. It also means that the method or software for calculating the annual energy consumption must be capable of modelling all Deemed-to-Satisfy Provisions in to . If the software does not have provisions for, say an "occupant activated device" in a Class 3 building, then the Performance Solution demonstrated to be compliant using would still need to include that device.
The following flowchart illustrates how can be used to assess different Performance Solutions.
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