What is Passivhaus?
Passivhaus is a German energy efficiency standard for how much energy a building uses for heating (and cooling). It requires a very low energy demand; approx. 90% less than current UK Building Regulations.
A by-product of the Passivhaus design is the high level of thermal comfort they provide their users. A Passivhaus will not have drafts or cold areas and will maintain a steady temperature through-out the year.
Passivhaus have a separate standard for works to an existing building; Enerphit. The energy demands are not quite as onerous as Passivhaus but still require very high levels of thermal efficiency.
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What is embodied energy?
Embodied energy accounts for the energy taken to build, produce, manufacture and deliver the materials and products selected. The importance of looking at embodied energy comes not just when selecting materials and construction methods but also when considering demolition or re-use.
What is fabric first?
Fabric first is an approach to providing sustainable energy to a building. The principle is to ensure that as much of the heat added into a building is retained within the building rather than relying solely on sustainable energy supply. Only once a fabric first approach has been taken should the energy supply be considered.
Why is Passivhaus, energy efficiency and embodied energy important?
The UK government has signed into law a commitment to bring all greenhouse gas emissions to net zero by 2050. The UK Green Building Council estimate that the built environment accounts for 40% of all carbon emissions. This means that the construction industry as a whole has a large part to play in contributing towards the goal of net zero.
As part of meeting the 2050 targets the Building Regulations are being updated in a series of phases to require improvements to the energy efficiency of new buildings. Whilst there remains the question of whether the step changes go far enough in the interim, by 2050 new build buildings will need to be near the Passivhaus standard.
What about existing buildings?
80% of the buildings that will be around in 2050 have already been built. This means significant changes to most existing buildings, they will need to change the type of energy supplied (no more gas) and undergo improvements to their energy efficiency.
What is retrofit?
Retrofit and deep retrofit are construction industry terms for projects that make significant energy efficiency improvements to an existing building. These types of projects are often carried out to the Passivhaus Enerphit standard.