How to Become Passive House Certified
Passive Houses have been around since the nineties, yet recently they’ve been attracting more interest in the Australian building industry. Increasingly, they’re being seen as a strategic design approach to ensure long-term sustainability that significantly lowers energy consumption, while also ensuring that dwellings meet the updated requirements of the National Construction Code (NCC) 2022.
These updates to the NCC focus on energy efficiency, with architects and builders required to meet stringent guidelines. Thermal performance requirements were raised to 7 stars under the Nationwide House Energy Rating Scheme (NatHERS), and residences must meet a new ‘whole-of-home’ energy rating.
However, receiving certification as a Passive House requires careful planning, design and execution. It means meeting specific energy-efficient standards for building construction and design, which include the installation of high-performance windows such as those sustainably manufactured by Thermotek.
Let’s explore the requirements of Passive House certification plus how it helps architects and builders meet the latest NCC requirements.
What defines a ‘Passive House’?
A Passive House takes a ‘fabric first’ approach. It follows a set of design standards that delivers energy-efficient buildings, that are also comfortable and healthy for residents.
The building envelope does the work to create a comfortable environment, rather than any energy appliances.
The first Passive House was built by Dr Wolfgang Feist in Germany in 1991, and still performs as predicted after more than three decades.
Dr Feist then established the Passivhaus Institut in 1996 as an independent research institute to promote the principles around the world and to govern certification.
The definition of a Certified Passive House is:
… a building, for which thermal comfort (ISO 7730) can be achieved solely by post-heating or post-cooling of the fresh air mass, which is required to achieve sufficient indoor air quality conditions, without the need for additional recirculation of air.
Passivhaus Institut (PHI)
A Passive House is appropriately insulated, airtight, has quality windows and reliable ventilation systems with heat recovery.
What does the Passive House certification process entail?
There are Passive House certifiers all over the world who undertake a stringent quality assurance process to make sure that the design and build meets the standards required by the Passivhaus Institut.
It does not set exact guidelines on how passive design is achieved but instead has performance metrics which must be met. These are:
- Thermal comfort during winter (20°C minimum) as well as in summer, with not more than 10% of the hours in a given year over 25°C.
- Heating demand 15kWh/m2/yr or heating load 10W/m2.
- Cooling demand 15kWh/m2/yr (in humid climates this allowance increases to allow for dehumidification) or cooling load 10W/m2 (if installed)
- Humidity must not exceed 12g/kg for more than 20% of the year (~60%RH at 25°C).
- Airtightness must be 0.6ACH50 or lower and be verified on site.
- Overall energy use (Primary energy renewable (PER) must not exceed 60kwh/m2/yr. When calculating overall energy use, Passive House includes whole-of-building energy; this includes heating and cooling, hot water, lighting, fixed appliances and an allowance for consumer electronics.
Passive Houses are usually built from scratch, but dwellings can also be retrofitted to meet the above criteria.
How does a Passive House achieve this through design?
There are five key design principles which form the basis of ensuring energy efficiency and meeting the certification standards for a Passive House.
- Airtightness
Passive Houses have an airtight building envelope. In practice, this means that there are a very limited amount of gaps and cracks, reducing drafts and giving residents complete control over the internal environment.
- Thermal insulation
Excellent insulation is key, as it provides a sufficient layer between the heated or cooled inside environment and the unpredictable outdoors. This improves comfort and reduces condensation by minimising cold surfaces.
- Mechanical ventilation heat recovery (MVHR)
The inclusion of a mechanical heat recovery system means residents don’t need to open windows for good air quality. This kind of unit effectively salvages heated and cooled air that would otherwise be wasted while also filtering the air that’s coming into the building.
This means cleaner air plus a lower risk of condensation.
- No thermal bridges
‘Thermal Bridges’ are areas that cause increased heat consumption and increased condensation risk. The insulation needs to be a good thickness and continuous.
Having no thermal bridges means keeping penetrations through the insulation to a minimum. If they absolutely must be made for construction purposes, it should be done with materials which are less conductive, like timber. Or thermal breaks can be used, whereby a material that doesn’t conduct heat well separates two conductive materials (like metal). - High-performance windows
Windows should have excellent levels of insulation and be double or triple glazed with thermally broken or non-metal frames.
The size of the windows should also be consistent with the building envelope, to allow for the right amount of solar radiation in summer and winter.
Double or triple glazed windows like Thermotek’s reduce the heat flow outwards in winter and inwards in summer by a factor of up to 6, compared with single glazing.
The size of the windows should also be consistent with the building envelope, to allow for the right amount of solar radiation in summer and winter.
Double or triple glazed windows like Thermotek’s reduce the heat flow outwards in winter and inwards in summer by a factor of up to 6, compared with single glazing.
Thermotek’s high-performance windows meet passive design standards
Thermotek windows and doors are crafted for outstanding thermal performance and energy efficiency, which mean they are the perfect match for Passive House design.
The sustainable uPVC used has high thermal insulation properties, while the IGUs (insulated glass units) use standard Low-E glazing with argon gas.
When it comes to airtightness, Thermotek frames consist of various fusion welded air chambers. These give a superior seal which optimises insulation, and the dual TPE (thermoplastic elastomer) seals further enhance thermal performance.
The gap between the two panes in Thermotek windows is the main source of insulation, which slows down thermal transfer by conduction. The systems slow down air circulation to reduce the amount of heat lost in winter and gained in summer.
Thermotek window and door systems keep a home’s internal temperature stable, cutting down the need for heating and cooling appliances or negating them altogether.
How does Passive House design work in tandem with the NCC 2022’s energy efficiency requirements?
The recent updates to the National Construction Code (NCC) made two key changes to residential works, including apartment buildings:
- Thermal performance requirements were raised to 7 stars under the Nationwide House Energy Rating Scheme (NatHERS).
- A new Whole-of-Home Rating must be met by new homes. This applies to heating and cooling, hot water systems, lighting, swimming pool and spa pumps, windows and doors. Renewable and sustainable energy systems, such as solar panels, aren’t mandatory but can be installed to keep a home’s energy under budget.
Achieving Passive House certification means it’s almost a given that these requirements have also been met. In fact, the certification process by the Passivhaus Institut is considered more arduous than most other building codes in the world.
Global research by the Passivhaus Institut shows that a Certified Passive House achieves up to a 90% reduction in energy demand compared to most dwellings.
The Institut also offers thermal modelling software which harnesses climate data from national organisations (e.g., the Bureau of Meteorology) to project monthly heating and cooling demands and overall energy consumption.
Passive House certification for Australian homes is an integrated, science-based approach to ensure buildings perform as predicted and avoid future air quality, condensation and mould problems.
Achieving affordable passive design with Thermotek
One objection the building industry has traditionally raised to Passive Houses is that the initial outlay on materials can be higher. However, this is offset in the long run by savings on energy bills and a positive impact on the environment.
It is of course a concern for architects and builders to keep costs down and stay within a project budget. Yet it is possible to find reasonable passive design solutions.
As a sustainable manufacturer of high-performance windows and doors, Thermotek has finely tuned our production processes to offer affordable solutions to the Australian market.
Engineered in Germany but manufactured locally, the Thermotek Eco Series windows and door system is a cost-effective solution for Australian residential developments that are required to meet energy ratings. It harnesses the 3 chamber Ideal 2000 uPVC profile by Aluplast.
The streamlined 60mm profile is versatile and fully insulated, with a dual seals frame that caters for a wide range of opening configurations.
For Passive Houses, the materials we use are more cost effective than thermally broken aluminium, allowing architects and builders to achieve a genuinely high NatHERS energy rating without the hefty price tag that can come with other sustainable solutions.
We are also a low waste manufacturer. All our products are 100% recyclable and manufactured in a sustainable way.
Start the journey to Passive House certification today
The dedicated team at Thermotek are experts when it comes to true passive design. Get in touch today to find out more about using our window and door systems in your residential or commercial building project.
