Where EnerPHit fits into Retrofits

Category:

The Built Environment

Tags:

EnerPHit, Retrofit, Passivhaus

EnerPHit is the quality standard awarded by ‘Passivhaus Institut’ to a deep retrofit of an existing building which meet a specific ‘EnerPHit’ criteria. These criteria require a lower threshold of energy efficiency compared to the Passivhaus to reflect the more challenging nature of improving an existing building.   “A Passivhaus is a building for which thermal comfort can be achieved solely by post-heating or post-cooling of the fresh air mass, which is required to achieve sufficient indoor air quality conditions – without the need for additional recirculation of air.”     Inherent physical limitations The EnerPHit Standard has been developed as a good practice refurbishment guide for Passivhaus. The first ‘Passivhaus’ low energy construction standard is credited to Dr. Wolfgang Feist of the Passivhaus Institut, which was completed in Darmstadt, Germany in 1990. Passive Houses "were defined as buildings which have an extremely small heating energy demand even in the Central European climate and therefore need no active heating.  Such houses can be kept warm 'passively', solely by using the existing internal heat sources and the solar energy entering through the windows as well as by the minimal heating of incoming fresh air." Due to the inherent physical limitations of working with an existing structure it has been recognised by the Passivhaus Institut that the stringent energy efficiency requirements for full ‘Passivhaus’ certification are unfeasible. The more achievable ‘EnerPHit’ certification has been designed for this purpose.     EnerPHit retrofits are sometimes referred to as deep retrofits. However, not all deep retrofits qualify for EnerPHit certification
The greatest challenge presented by an existing building when attempting to achieve the EnerPHit standard is the pre-existing fabric of the building. In some cases the whole internal structure of a building is removed and rebuilt to the Passivhaus standard. This drastic measure is in general, deemed unnecessary. A comfortable, energy efficient home can usually be achieved through less drastic measures and the EnerPHit standard attained. Pre-existing structures in general, will present the architect with a number of ‘cold bridges’. Cold bridges are areas within the fabric of the building where one building component meets another. In a Passivhaus design a continuous insulating membrane wraps around the interior of the building. This insulating envelop makes the building airtight, allowing total control of the internal temperature by the heating and cooling of the circulating fresh air. Existing buildings have their individual orientation, which was probably not influenced by its solar power generating potential, nor where the cooling benefits of shade and ventilation factors in the original design process. Many older properties are situated in conservation areas, or are protected under the properties Listed status criteria. In these cases only those changes which are deemed as suitable within the set of rules that apply the individual property can be undertaken. Often compromises need to be made in order to apply the necessary improvements to the protected building. The installation of triple glazing through the addition of secondary glazing units behind the existing primary windows is often seen as non-invasive, as it is totally reversible