The Passive House Standard is the leading energy-efficient construction design in the world . With quality, comfort and energy efficiency at its core, the passive house design does not require heating or air conditioning systems. Plus, its durable design protects the building’s structure.
To achieve the optimal passive house design, you need to take five principles into account:
- High-quality insulation
- Robust windows
- Airtight construction
- Thermal-bridge free
- Heat recovery ventilation
An optimal passive house design prevents heat loss in winter and excessive heat gain in summer.
Insulating the envelope of the building—floor, walls, roof—is crucial to achieving the optimal passive house design. In most buildings, the outer structure is not sealed completely, allowing the warmth to escape. This, in turn, increases the amount spent on heating bills within the house and wastes energy.
A passive house design focuses on high-quality insulation made of low-conductivity materials and placed within the walls. Improved insulation also creates better soundproofing, durability and building resilience. There are many ways to begin insulating your home to achieve a passive house design.
To optimise your passive housing build, consider not just how much insulation you use but whether it is used effectively. It performs best when it wraps the property uninterrupted by other materials. In places, this is not always possible—when other material bypasses the insulation, this creates a thermal bridge that reduces the insulation’s effectiveness.
Some designers build the entire home from insulation materials, such as wood fibre or clay bricks.
Windows are another part of the construct that are susceptible to heat loss. Poorly fitted windows can let drafts in as well as noise pollution. As windows provide light and visibility, they cannot be insulated like the walls.
Therefore, the Passive House Standard requires high performing windows that are double or triple glazed. Passive house glazing has non-conductive framing, insulated framing, argon gas fill, and non-conductive spacers.
It is not just the high-quality windows that optimise the passive house design, but their placing within the building. As passive housing takes advantage of solar heating, the windows have to be placed appropriately to offset the amount of heat the home needs in winter with shading to prevent overheating in summer.
Each passive house builder has an ideal number of windows to suit each construction; too many and you lose heat, too few, and you cannot take advantage of the sun’s free heat.
Heat is also lost through air escaping. The building’s exterior creates a barrier to stop the free movement of air between the outside and inside. However, gaps in this barrier can create drafts and heat loss. Poor construction or too many interruptions in the barrier can lead to uncontrolled air movement.
This can lead to many issues for the homeowner. Heating bills increase as you struggle to maintain the temperature throughout the house. Discomfort from cold air leaking into the home, especially near the walls. Risk of moisture and condensation that leads to mould. While every house needs air exchange for ventilation purposes, out of control air movement can harm your property.
To achieve the Passive House Standard, the building is required to have less than 0.6 air changes per hour. Careful planning in the design stage and meticulous attention to detail is needed to perfect the airtight construction of the property.
Thermal Bridge Free
Thermal bridges (also known as a cold bridge, heat bridge or thermal bypass) is part of the construction where the material has a higher thermal conductivity than surrounding materials. For example, a metal bypass is highly conductive. Within the insulation, the metal creates a path of least resistance for the heat transfer and reduces the effectiveness of the insulation.
The Passive House Standard does not just aim to minimise thermal bridges but also to be thermal bridge free. In places such as where a window meets a wall or where a balcony attaches to the wall, builders and designers can take care to reduce thermal bridging.
To avoid thermal bridging, try to make architectural design changes. Use self-supported decks to reduce the number of balconies attached to the exterior of the walls. While ridding the building of all thermal bridges is not always possible, extra attention should be paid to reducing them.
Window-to-wall connections can cause some of the most significant thermal bridges. The installation of the window requires careful design to minimise heat loss. To fit a window while reducing thermal bridging, position the window to line up with the insulation layer, over-insulate the front of the frame and minimise how far closure flashings go through the rough opening.
After all that effort making the property airtight, there still needs to be some ventilation and movement of air. Controlled ventilation invites in the fresh air and removes built-up pollutants, odours, CO2, and moisture.
One such passive house ventilation system is on the roof. Dry fixed roofing is the construction of the roof using mechanical fixings, such as screws and fastenings rather than mortar, allowing space for a natural cooling system. Air circulates beneath the tiles, preventing extra heat from descending into the home’s interior.
Dry fixed roofing can save the property 5% on utility bills to heat and cool the property and is a great addition to your passive house.
The optimal passive house design requires meticulous attention to detail during the planning stages. It focuses on reducing thermal bridges, creating an airtight structure and optimising the effectiveness of insulation. Saving homeowners money and built to last, the Passive House Standard is a world-leading energy-efficient design.