The Modular Path to Passive House

Here at HOW Social Construct, our purpose is to leverage the benefits of modular construction to deliver healthy, comfortable, energy efficient homes.

Modular construction readily lends itself to design innovations which deliver improved amenity for occupants. Enhanced build quality and high thermal and acoustic performance are just a few of the factors which are leading the charge in the case for this progressive but well established building method.

Recently, the HOW team was introduced to Passive House (Passivehaus), a rapidly growing, internationally recognised building standard which utilises five key design principles to create built environments which are truly energy efficient, comfortable, healthy and at the same time affordable.

For HOW, Passive House is a rigorous and scientific framework which could be overlayed and would allow us to capture and enhance our existing features and benefits. It will facilitate an evolution of our modular products to an even higher level of performance. We will produce ultra-low energy buildings that require little energy for heating or cooling, reducing the building’s ecological footprint.

What are the benefits?

Health Benefits – A controlled mechanical ventilation system imperceptibly supplies constantly filtered fresh air, making for superior air quality without unpleasant draughts. A highly efficient heat recovery unit allows for the heat or cool contained in the exhaust air to be re-used and keeps the humidity inside the home at a comfortable 30 to 60 percent. This creates an environment which is free from mould and mildew.

Thermal Comfort – Passive house design strives to maintain a comfortable, even temperature throughout the home, with low temperature variations from room to room. The difference between radiant temperature (i.e., the temperature of windows, doors and other surfaces) and air temperature remains small, helping to eliminate drafts. High-performance windows and superior insulation also help to keep the inside of the passive house extremely quiet.

Reduction in energy use and utility costs – Can you imagine living in a home that keeps you warm and cosy all winter, without running the heater? How about a home that stays cool and comfortable even in the tropical midsummer heat? Heating and cooling accounts for 40% of an Australian home’s energy cost and building to a Passive House standard can reduce that cost by up to 90%!


How is the Passive House standard achieved?

Designing and building your home to meet the rigorous Passive House standard is a detailed and complex process which uses specialist software, however the core principles are simple to understand.

The Passive House methodology is underpinned by five key components relating to how the home is designed and constructed. Let’s look at how it all works and why modular construction is an ideal solution…

Thermal Insulation – Sufficient insulation is required within the building’s envelope, providing enough thermal separation between the heated or cooled conditioned inside environment and the outdoors. This improves thermal comfort and reduces the risk of condensation (no more cold internal surfaces in winter!)

The modular design and manufacturing process allows a range of insulation upgrades and solutions to help achieve the required r-values as calculated by the Passive House Planning Software. In NSW, our existing insulations standards almost meet the Passive House requirements so only minor upgrades are required.

Thermal Bridge Free Construction – Insulation not only needs to be sufficient in thickness but also needs to be continuous. This means keeping penetrations through the insulation to an absolute minimum, and if not avoidable then using materials that are less conductive to heat (i.e. timber in place of metal) and/or incorporating thermal breaks (whereby a material that doesn’t conduct heat separates the two conductive elements). Otherwise, your well insulated building will have a number of thermal highways that will cause increased energy consumption and increased condensation risk whilst impacting thermal comfort.

The modular design and manufacturing process is adaptable enough to allow for the identification of thermal highways and the introduction of thermal break solutions in order to achieve the rigorous Passive House standards.

Airtightness – Tradition Australian home construction methods provide a variety of locations for heat or cool energy to escape, making them inefficient and costly to manage. An essential part of every Passive House is an air tight building envelope. This ensures that there are only a very limited number of gaps and cracks within your envelope, giving you full control over your internal environment and significantly improving thermal comfort. This means no more draughts!

The modules in modular construction are built from extremely robust structural elements. Rigid frames and walls are fully welded creating a largely airtight box. The only locations where air tightness needs to be assured is doors and windows and services ducts as these are the only possible locations for leakage.

Mechanical Ventilation Heat Recovery – Now this doesn’t mean that you can’t open your windows! The incorporation of a mechanical ventilation unit means that you simply don’t need to rely on opening them to achieve good indoor air quality. The unit effectively recovers heat and cool that would otherwise be wasted whilst also filtering the air that’s coming into the building. This leads to fewer pollutants in the air and a lower risk of condensation meaning a healthier indoors.

Our modular products have HVAC systems installed during the manufacturing process which can easily be replaced with more efficient heat recovery ventilation systems.

Passive House (High Performance) Windows – It’s not just the solid areas of your building envelope that need to have good levels of insulation but your windows too. No more single glazing, but instead low-emissivity double or triple glazing with thermally broken or non-metal frames. As part of the Passive House design process, the size of the windows should be appropriate to each orientation, to allow solar radiation to penetrate during the winter months (free heating!) but not result in too much solar radiation during the summer.

Our modular products already come with double glazing as standard so an upgrade to thermally broken aluminium joinery is all that is required.


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