Passivhaus is a leading standard in energy efficient design.
It is a design methodology, construction concept and wellness standard based on tested building physics that delivers low energy design solutions, that avoid draughts, mould growth, and issues associated with overheating. At FMA we have our own certified Passivhaus designer.
Passivhaus is a method by which building form, orientation, fabric performance and glazing amounts are optimised to minimise operational energy use. Typically mechanical systems are used with high efficiency heat recovery to provide warmed ‘tempered’ fresh air.
The Need for Low Energy Buildings
As the UK energy grid decarbonises and the use of gas for heating becomes less common, homeowners and businesses will increasingly turn to electricity to provide space and water heating. At the current time, there is insufficient electricity in the grid to provide space heating for all UK homes at the current level, as a low energy building, a Passivhaus will minimise the electricity required for a comfortable internal environment and play a vital role in the transition to net zero.
Enerphit
The Enerphit design standard was developed by the Passivhaus institute for refurbishments of existing buildings. Recognising that trying to bring an existing building up to full Passivhaus standard can be challenging, this standard has lower performance criteria but still delivers significant energy savings with achievable solutions. In a similar fashion to the new build standard, it requires high levels of fabric performance, air tightness, comfort, and wellness criteria.
Comfort and Wellness Standard
Fresh air is a requirement, not just for comfort but for healthy living, the standard requires that sufficient levels of fresh air are provided through out the dwelling, incoming air is warmed by the outgoing ventilation which avoids draughts, moisture build up is avoided and combined with the insulated fabric moisture build up is prevented that limits mould growth.
To achieve the standard, the design requires shading methods to be used that will prevent internal temperatures exceeding a comfortable level for more than 10% of the year.
Performance Gap
Buildings that comply at design and construction stage with the Passivhaus standard typically have very little difference between the anticipated performance and the ‘in-use’ figures. The reduction in energy use means that low carbon design is achieved by being ‘lean’ with energy rather than using renewables that have an obsolescence and need to be replaced.
Modelling and Certification
At FMA we can follow this methodology and design standards to obtain the passivhaus certification. The building needs to be modelled in the Passivhaus Planning Package software (PHPP) and documented throughout all stages of design and construction. This information is passed to an accredited building certifier independent of the designers who will review the design and evidence and will issue certification if the building is compliant.