Passive House is a building standard that is truly energy efficient, comfortable and affordable at the same time. Passive House is not a brand name, but a tried and true construction concept that can be applied by anyone, anywhere.
Yet, a Passive House is more than just a low-energy building:
- Passive Houses allow for space heating and cooling related energy savings of up to 90% compared with typical building stock and over 75% compared to average new builds. Passive Houses use less than 1.5 l of oil or 1.5m3 of gas to heat one square meter of living space for a year – substantially less than common “low-energy” buildings. Vast energy savings have been demonstrated in warm climates where typical buildings also require active cooling.
- Passive Houses make efficient use of the sun, internal heat sources and heat recovery, rendering conventional heating systems unnecessary throughout even the coldest of winters. During warmer months, Passive Houses make use of passive cooling techniques such as strategic shading to keep comfortably cool.
- Passive Houses are praised for the high level of comfort they offer. Internal surface temperatures vary little from indoor air temperatures, even in the face of extreme outdoor temperatures. Special windows and a building envelope consisting of a highly insulated roof and floor slab as well as highly insulated exterior walls keep the desired warmth in the house – or undesirable heat out.
- A ventilation system imperceptibly supplies constant fresh air, making for superior air quality without unpleasant draughts. A highly efficient heat recovery unit allows for the heat contained in the exhaust air to be re-used.
The documents used for certifying Passive Houses have been simplified and a new category for certifying ‘PHI Low Energy Building Standard’ has been created. The revised standards have the purpose of making the assessment criteria clearer and more comprehensible.
The Passive House Standard
The Passive House Standard provides an effective way of achieving a very efficient building. It is split into 3 categories, Passive House Classic, Plus or Premium and they can be achieved depending on the demand and generation of renewable primary energy (PER). The space heating and airtightness required for standard Passive House certification can be seen in Table 1 below.
Table 1 - Passive House Criteria
PHI Low Energy Building Standard
The Passive House Institute have created a new standard for the certification and accreditation of Passive House buildings called the “PHI Low Energy Building Standard”. This standard is suitable for buildings which do not meet all the stringent requirements to achieve Passive House Standard Certification.
Table 2 - PHI Low Energy Building criteria
The heating demand and air tightness values for Passive House Standard can be seen in Table 1 above (top). A Heating demand of 15kWh/(m2a) and an air tightness of 0.6 m3/hr/m2@50Pa is required. These criteria are extremely stringent and can be hard to achieve and maintain throughout the build. In comparison, the requirements for this new standard (Low Energy Building) can be seen in Table 2 above. A Heating demand of 30kWh/(m2a) and an air tightness of 1 m3/hr/m2@50Pa are required for accreditation. There is a difference of 0.4 m3/hr/m2@50Pa and 15kWh/(m2a) between the traditional standard and the new Low Energy Building Standard, this results in a much more attainable target for home owners.
The new standard will hopefully encourage more people to consider certification. By designing and building to Passive House standards, the home owner’s energy bills will be reduced. This reduction in energy bills will offset the increased cost of the construction. To achieve the new standard, the same construction techniques and materials are employed as are used to achieve the traditional Passive House Standard. This new standard is much easier to achieve and provide the home owner with an extremely energy efficient house.
Criteria for the Passive House, EnerPHit and PHI Low Energy Building Standard. [online] Available at http://passiv.de/en/02_informations/01_whatisapassivehouse/01_whatisapassivehouse.htm > [Accessed 29 September 2015]