Passive House project relies on heat recovery ventilation system
A Passive House project with 14 properties was designed to increase the number of homes with affordable rent and low living costs in Hatfield Heath, Hertsfordshire in the United Kingdom.
The project of three three rows of terraced properties with 13 homes for affordable rent and one for shared ownership was built after a housing needs survey prompted the local parish council to approach Hastoe Housing Association, a specialist rural housing provider, to take on the project.
Hastoe is well known for its ability to provide good standards of design and construction for social housing, particularly rural exception sites and decided to use the Passive House standard for this project combined with their chosen regulations, codes and standards.
Passive House developments are required to be energy efficient, comfortable and affordable, so it was essential that a quality heat recovery (MVHR) ventilation system was specified, enabling the properties to meet stringent energy performance criteria and achieve a comfortable all-year-round indoor climate.
Low energy solutions for the social sector
Following a suggestion from the main contractor DCH Construction thatZehnder’s Comfo Air CA200 model would be the most appropriate unit to use in the development, architects Parsons + Whittley approached Zehnder for more information and advice. With many years’ experience of working on Passive House developments, Zehnder’s experienced team understands inherently how to design suitable Passive House certified ventilation systems and were able to advise on the benefits of the CA200 as well as on its installation in the development at Hatfield Heath.
Air quality and comfort
Guaranteeing the provision of optimum quality indoor air all year round, the CA200 is designed specifically for properties up to 110m², so was an ideal choice. Furthermore, while the average MVHR unit on the market stands at between 75 and 80 per cent efficiency, Zehnder’s CA200 model offers an outstanding 92% heat exchange efficiency rate. It also has a filtered bypass, which ensures that during warmer summer months the internal environment remains comfortable. Ventilation is provided continuously without recovering the heat from extract air - which can assist with reducing summertime overheating.
Cost saving benefits
The energy consumption is going to be measured over the first 12 months following completion, but it is to be expected that as with all Passive House constructions the running costs will be markedly lower than a regular New Build, making them truly affordable for future tenants.
“The project was completed in January 2015 and the commissioning process went very smoothly with all dwellings passing first attempt," said Dan Higginbotham from architects Parsons + Whittley.
"We believe strongly in the Passive House approach and the equipment and technical support provided by Zehnder gives us confidence in the occupants of these dwellings being fully satisfied with both comfort and energy use.
“Ventilation is a crucial aspect of the Passive House build in ensuring both comfortable, quality air and heat efficiency so we were delighted to be partnering with MVHR Passive House experts, Zehnder. Working closely with their team, we were able to ensure that effective and efficient mechanical ventilation heat recovery solutions were provided for each style and size of property.”
Read more about Passive House construction.
Companies: Zehnder America