energy research building code of australia vol 1 pdf
TRANSCRIPT
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
1/19
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
2/19
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.
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
3/19
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
4/19
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
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
5/19
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
2
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
6/19
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
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
7/19
4
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.
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
8/19
5
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).
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
9/19
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
6
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
10/19
7
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.
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
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
11/19
8
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
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
12/19
9
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.
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
13/19
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
10
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.
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
14/19
11
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.
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
15/19
12
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
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
16/19
13
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
4 star rating 23 reduction
Higher insulation + double glazing (low -e) 21 reducti on
3 star rating 14 reduction
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
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
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
17/19
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
14
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.
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
18/19
15
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.
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
-
8/2/2019 Energy Research Building Code of Australia Vol 1 PDF
19/19