Building Energy Efficiency & Sustainability
House Energy Ratings
Hobart Energy Efficiency are ABSA accredited building thermal performance assessors who can audit, assess and certify to satisfy current BCA 6 star energy efficiency requirements. We conduct house energy ratings throughout Tasmania and Australia wide. As of May 1 2013, Tasmania joined the remainder of Australia in going from 5 to 6 stars in relation to minimum energy efficiency requirements under the Building Code of Australia (BCA). This has meant that any new building is subject to more stringent energy efficiency requirements. Many architects and building designers are finding that their plans are not complying with the provisions of the BCA, therefore are requiring a house energy rating (building thermal performance assessment) for BCA compliance.
A house energy rating highlights areas of thermal inefficiency, which allows for changes in design to comply with the National House Energy Rating Scheme (NatHERS)
What types of buildings do the “6-Star” requirements apply to?
- All Class 1 buildings (detached house, unit or town house)
- All Class 2 buildings (apartments) and
- Class 10a buildings (such as garage) that have a conditioned space (heated or cooled) attached to a Class 1 building.
The 6-Star requirements also apply to new work on an existing residential building such as additions, extensions and alterations.
What are the main changes introduced by the “6-Star” requirements?
- more insulation is needed to meet increased minimum R values
- more stringent glazing provisions
- compensation for ceiling insulation loss from openings such as exhaust vents and downlights
- new requirements for fixed lighting.
Achieving the “6 Star” level
“6 Star” refers to the required level of thermal performance for the building. That level can be achieved by either:
•complying with the relevant elemental Deemed-to-Satisfy Provisions in the BCA; or
•achieving an energy rating of not less than 6 Stars using house energy rating software that complies with the National House Energy Rating Scheme (NatHERS);or
•reducing the heating or cooling loads (verified by energy rating software) and complying with specific energy-saving features such as the testing and installation of insulation, thermal breaks, compensation for downlights, floor edge insulation and building sealing.
How is compliance with “6-Star” verified?
The Building Act 2000 requires a permit for new building work to ensure it will comply with the National Construction Code (NCC). The design of new homes and extensions is assessed against the NCC by a building surveyor for the issue of a Certificate of Likely Compliance. This assessment includes checking for compliance with the 6-Star energy efficiency requirements.
Complete Service from House Energy Rating to Building Completion.
I offer a complete service, not only providing you with a House Energy Rating but also inspecting your home during construction to ensure it is sufficiently air tight, that sisalation has been fitted correctly, particularly around openings such as windows and doors and that wall, underfloor and ceiling insulation has been fitted with no gaps.
In Tasmania there are no mandatory provisions for building surveyors to inspect any of the above.
Under the Building Regulations 2004, the Mandatory inspection stages are:
(a) covering in the foundations;
(b) pouring structural concrete;
(c) cladding or building in the structural framework;
(d) completing the building work;
(e) any other stage of work determined by the building surveyor and listed on the certificate of likely compliance.
Finally, I conduct a blower door test to ensure your home is sufficiently air tight (the energy rating software assumes it will be, so it makes sense to ensure it is) otherwise the energy rating is very misleading. The blower door test will also determine if your home will require mechanical ventilation such as a heat recovery ventilation system or not. Many new homes are being constructed with the builder and buyers not knowing that condensation and unhealthy home issues will arise once occupied.
Blower door tests are a mandatory inspection stage prior to occupancy in other western countries.It really does pay to ensure your home has been constructed with energy efficiency in mind. Not only will it provide greater thermal comfort, but also minimise heating costs.(60% of your electricity bill in Tasmania is consumed as heating)
We are accredited with the Association of Building Sustainability Assessors (ABSA) – Accreditation No 70131 and use FirstRate5 2nd generation software. In order to assess the thermal performance of a building, the software takes the following factors into account:climate and wind, location, orientation, form and design, building fabric, glazing and cross ventilation, as well as occupant behaviour.
We can help you achieve a comfortable, energy efficient and environmentally friendly home.
What is required for the assessment?
- Site plan indicating the orientation of the buildings and any overshadowing structures.
- Plans, elevations and sections showing window sizes, eaves width and building fabric details.
- Details on windows and glazing (specific manufacturer and window type if available.
- Floor covering details.
Final documentation includes:
- FirstRate5 software documentation
- ABSA Assessor Certificate, Thermal Performance Certificate and Form 55 as required by the building surveyor.
- Certified drawings with relevant ABSA stamp.
- ABSA NatHERS House Energy Rating Certificate.
- Submission of certified drawings and documentation via email or hard copy.
What is the cost?
Assessment and documentation costs are quoted on an individual basis based on the size and complexity of the project. We generally require a set of plans prior to quoting a price.
Designing and constructing a “6-Star” energy efficient house
Designing and constructing a new home or extension to be 6-Star energy efficient will cost much less than attempting to refit an existing building. That is why the 6-Star requirement is mandatory for new work at the design or construction stage.
Homes incorporating sound environmental design principles can minimise heating and cooling bills and have a lasting positive impact on the environment by reducing greenhouses gases. Some of these principles include:
•site responsive design and appropriate house zoning orientation
•well insulated wall, floor and ceiling
•thermally efficient windows
•northerly orientation to gain maximum advantage from solar energy
•internal and external shading of windows and walls in summer.
Consider the climate zone location
The 6-Star energy efficiency requirements depend on the climate zone in which a house is located. Climate zones are determined on climatic data and there are two Tasmanian zones:
•zone 7 (covering most of the state including the Bass strait islands)
•zone 8 (covering only alpine areas above 900 metres).
Consider the orientation of the house on the block
Good solar orientation of a house has the potential to achieve substantial energy savings when combined with an efficient design. Houses built with a north facing orientation for the main living areas are more likely to easily achieve a 6-Star rating.
Houses with large areas of glazing facing south, west or east may still achieve 6-Star but are then likely to incur higher construction costs and on-going heating costs for the occupants.
Consider the envelope of the house
The design and construction of the house’s envelope – roof, external walls and floors – will have an effect on the thermal comfort of a house. To achieve a 6-Star rating, the following is required:
•insulation of roofs and ceilings
•insulation under suspended floors and also slabs on ground.It is recommended that slab edges be also insulated due to thermal bridging, as concrete itself has very poor insulation qualities.
•selection of appropriate glazing systems (windows and doors).Glazing is the weakest area of a home as far as energy efficiency goes, theefore it pays to spend as much money as you can afford on windows.I provide expert advice on glazing types and also energy efficient window frames.(Standard aluminium frames are best to be avoided due to their ability to allow heat and cold to travel directly through the frame, resulting in extremely poor enegy efficiency. Choose thermally broken aluminium,timber, upvc or pultruded fibreglass for the greatest enegy efficiency)
•consideration of the number and size of roof lights (skylights) and ceiling penetrations including downlights. Ventilated downlights are best avoided due to required insulation gaps and also air leakage.
•sealing of openings and gaps to prevent draughts and covering of disused fireplaces(A Blower Door Test will verify if your home is sufficiently draught proofed)
•The Australian Building Codes Board (includes Tasmanian Climate Zone Map) http://www.abcb.gov.au
•Nationwide House Energy Rating Scheme (NatHERS) http://www.nathers.gov.au
•Commonwealth Government Department of Climate Change http://www.climatechange.gov.au
•Living Greener http://www.livinggreener.gov.au
•Tasmanian Government Energy Efficiency site “Earn Your Stars” http://www.climatechange.tas.gov.au