Passivhaus buildings provide a high level of comfort while using very little energy for heating and cooling. To achieve this a great deal of attention goes into the design, detailing and construction to ensure that the building adheres to the principles developed by the Passivhaus Institute in Germany. A certification program was created to act as a quality assurance process.
Passivhaus achieve savings of up to 90% in heating and cooling requirements. The reductions are so significant that a typical Passivhaus with a 5 star heat pump air-conditioner may use about the same amount of electricity for heating and cooling as an average fridge. The design of the hot water system then has a greater impact on the total energy used. By using PHPP as a design tool and looking at total energy consumption we are able to reduce the ecological footprint of the building. Because about 80% of the total building carbon output is created during its use the Passivhaus standard provides a robust method to substantially reduce the buildings lifetime carbon footprint.
These 5 principles were all developed well before the first Passivhaus was built. These are commonsense principles based on sound building science. For any building to achieve the levels of efficiency that characterize a high-performance building, it will need to utilize all the 5 principles listed below and apply them in the correct manner. The Passivhaus Institute set out a number of performance criteria and developed the software (PHPP) to be able to accurately assess this.
The main problem with insulation in newly built houses in Adelaide is not the amount of insulation, but the quality of the installation. Standards in general are very poor. The amount of insulation required in a well designed Passivhaus need only be a little more than the deemed to comply minimum standards.
However we do need to get away from aiming for the bare minimum which is what typically happens with new-builds in Australia. That is just a race to the bottom. So it is a good idea to put in extra insulation to give you more flexibility in the overall design.
Windows are by far the weakest link in Adelaide new-builds. Most new houses will use basic aluminium single glazed windows. From a thermal transmittance viewpoint these are the worst type of window you can use.
In a Passivhaus, windows are a key defence point. The typical solution is a high quality and high performance (usually German designed) UPVC or timber double glazed windows and external doors. Thermally broken aluminium can also be used but they will need to be of a higher quality than what is generally available in the market. The windows need to be well designed and air-tight. Special attention needs to be placed on the various components, glazing and method of installation.
A thermal bridge is a physical pathway for heat to easily transfer in and out of the building. For inefficient buildings these bridges are not as critical because the whole building envelope may be transferring a significant amount of heat so the significance is lessened.
In a Passivhaus, because the external envelope is optimized and transfers a minimal amount of heat, the impact of a thermal bridge is magnified and can form a significant proportion of the overall heat transfer. That is why The Passivhaus standard aims for a thermal bridge construction to ensure a high quality building envelope that delivers high levels of comfort and energy efficiency.
This is the key element to any high performance building. It is also the easiest one to mess up so great care needs to to be taken during the design and construction phases.
The typical Australian new-build has an air-tightness of between 15 to 20 ACH@50Pa. Put simply, this means that in most new houses the volume of inside air will be replaced at least every 4 minutes (15 times per hour) when the wind pressure is 33 Km/hr of greater. In a Passivhaus the requirement is 0.6 ACH@50Pa or less. By providing a virtually leak free (but vapour open) enclosure you have control of your indoor air quality.
The “lungs” of a Passivhaus is the mechanical ventilation system with heat recovery (MVHR). It allows an air-tight home to still breathe when the windows are shut. The MVHR constantly exhausts the stale air and replaces it with filtered fresh air. The heat recovery unit is able to recover about 90% of the heat so that the cost of maintaining an even temperature is minimized.
The impact the balanced ventilation unit has on indoor comfort levels is significant because it provides a huge upgrade to the indoor air quality. Not only does it filter out any outdoor contaminants, it also removes any indoor volatile organic compounds (VOC’s) and air pollution that may occur from material off-gassing. The other significant benefit is that humidity levels are kept consistently low, thus preventing mould from occurring.
Every inch of our homes are not only beautifully designed, they are calculated and built to surpass the World’s most rigorous energy efficiency, comfort and sustainability standards for buildings. Every component, every wall, window and even appliance is taken into consideration when meeting the Passivhaus performance standards
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Main picture- Equinox Passivhaus, Bozhuretz, Kavarna, Bulgaria