Building a Passive House: Everything You Need to Know
They’re dry, they’re warm in the winter and cool in the summer – but there must be more to passive homes than that. Numerous health and environmental benefits are the main reason why more and more investors and future homeowners are choosing a passive concept over traditional homes. Let’s expand the topic and round up all the benefits of passive builds.
The Definition of Passive
The term passive, when used for homes, refers to a comfortable and healthy home whose energy demands, especially for heating and cooling, are exceptionally low.
Relying on the movement of the sun and innovative design, these homes have smartly designed insulation and ventilation to maintain their own temperature levels with little need for additional air conditioning. The first recorded passive house was built in Germany and featured a grass roof, wooden beams, wool insulation, and wood-chip wallpaper.
Why Are They So Efficient?
In a nutshell, a passive home is like a thermos bottle, but with great ventilation. Regardless of the size, a passive house needs continuous insulation all over, triple-pane windows, air-tight sealing, and an effective air quality system.
Passive homes are also designed to prevent thermal bridging when one material’s temperature transfers to another material through physical contact. By sealing off the interior thermally, the inside temperature is more stable and less dependent on the outside conditions. All these together can make a passive home up to 90% more energy-efficient than a regular house.
Choosing the Site
The building site and the surrounding features are the first things you should consider. A passive home is built to capitalise on solar gains, so in the northern hemisphere, the house should be oriented to the south as much as possible.
This means that the site itself should provide unobstructed views to the south, as this is where the bulk of the glazed surfaces will be. Mature trees, neighbouring buildings, and terrain elevation should also be considered, as they might cast a shadow or prevent the sun from heating your building all the way.
Takes on Design
As numerous highly efficient examples show, a passive house can have any design the client wishes, but the more complicated the design, the more time and money is needed to complete it. As mentioned already the orientation should be to south, or north, if you’re building south of the equator.
As the south rises in the east and sets in the west, you need to plan the spaces so that you move your activities in this pattern, for example from the kitchen to prepare and eat breakfast, to the dining room or study to the west.
Incorporated service zones are a common practice in modern buildings, and almost essential in passive houses. A service niche in the wall is useful for running plumbing and electrical lines and regulators, it also helps protect the airtightness of the envelope.
Most of the homeowners like the idea of grouping all the home’s utility systems into one maintenance hub and choose to buy their peace of mind with a better home insurance package, that covers damage to the building and contents resulting from escaping water, fire, gas explosion, etc. Upgrading your insurance makes more sense especially when you consider that materials and products that make the building sustainable cost noticeably more than traditional choices.
When planning the rooms and areas within your passive building, it’s always recommended to group the wet areas together. When rooms such as the kitchen, bathrooms, laundry, and the utility rooms are side to side, back to back, or over each other, you’re effectively reducing the length of plumbing, and saving energy through reduced heat losses throughout the building.
This way of thinking can ultimately determine your floor plan, with a compact form being the most energy- and cost-effective. On the other hand, weird-shaped buildings, although look more striking and innovative, may prevent you from achieving certification if their shape affects airtightness or thermal properties.
When you settle for the design, the next thing to consider is the building fabric components. This largely depends on the type of insulation used, the thermal performance of the materials, the U-value for the components and thermal bridging where components intersect.
For example, the foundation materials are critical for avoiding thermal bridging where the floor meets wall components. In return, walls should secure a continuous thermal envelope and maintain the desired airtightness. Closed panel timber frame kits, SIP (Structurally Insulated Panel) kits, and ICF (Insulated Concrete Forms) systems have proven to be quick to install and highly efficient in reducing air leaks and thermal breaks.
Thanks to their energy-efficiency, the maintenance costs of passive houses are significantly lower than in traditional homes, which makes them a popular option for both investors and first-time builders. As the materials used to build a highly-efficient envelope are driven down, we can expect to see more passive designs in our neighbourhoods.