What is the EnerPHit retrofit standard?
The EnerPHit standard is a Passive House standard intended for refurbishment projects. It allows for more wiggle room compared to the traditional standard to accommodate retrofitting challenges, while still achieving the superior comfort and performance Passive House buildings are known for.
EnerPHit social housing retrofit – project overview
This retrofit in Great Yarmouth was undertaken on a block of six flats owned by Great Yarmouth Borough Council. This block was chosen for the project due to its traditional 1950s style, a common typology across the UK. For this retrofit, we developed a new bracketed system that delivers a fast, efficient, and cost-effective deep retrofit solution. It can be adapted to suit any of the UK’s mixed typology of housing. The results of this EnerPHit social housing retrofit have been excellent and the system’s versatility has been proven.
New triple-glazed windows were installed within the cladding system, along with an individual Mechanical Ventilation with Heat Recovery (MVHR) system for each flat. This approach maximises the benefit of the retrofit with regards to achieving target CO2 and energy bill reductions. The retrofit achieved the EnerPHit retrofit standard (the Passivhaus standard for retrofit and refurbishment projects), with a space heating demand of 25 kWh/m2 and an airtightness of less than 1 ach-1 @50Pa.
“Over the lifetime of the new building, we expect a 75% reduction in heating demand and subsequently energy bills for residents. We will be working with Oxford Brookes University to monitor energy use and air quality in the building for the next year.”
Founder and MD, Beattie Passive
The challenges of this EnerPHit social housing retrofit
The retrofit was carried out on terrace style flats, therefore the way that the newly retrofitted structure interacted with the neighbouring properties required further innovation. How to deal with the existing balconies on each flat – and whether our system could incorporate them into the new design, or if they would have to be removed. We wanted the design to be aesthetically outstanding, to showcase our vision for the future of housing in Great Yarmouth.
We implemented a number of new innovations
GRP brackets and aluminium angles were used to create a frame upon the existing building. The GRP brackets prevent a thermal bridge from the aluminium angle back to the existing building. A fireproof board was fixed to the frame to form a cavity, into which high performance insulation was injected, forming a continuous layer of insulation around the building. The project’s airtightness strategy involved, at one point, the whole building being sprayed purple, using airtightness paint Purple Passive.
We located the six MVHR units within the roof space, with ducting running down to each flat inside the wall cavity.
Over the lifetime of the new building, we expect a 75% reduction in heating demand and subsequently energy bills for residents. We will be working with Oxford Brookes University to monitor energy use and air quality in the building for the next year.
Retrofit project benefits
Let’s take a look at the benefits of this EnerPHit social housing retrofit project.
- Lifting tenants out of fuel poverty – Expected 75% reduction in space heating requirements.
- Expected airtightness result of less than 1 ach-1 @50Pa.
- Limited Disturbance to residents – Residents remained at home for the duration of the retrofit.
- Healthier, more comfortable homes – individual MVHR system for each flat providing filtered, fresher air.
- A new look home – completely new, modernized external façade.
- Enhanced fire safety – Non-combustible materials, horizontal and vertical fire barriers between floors, all services are fitted with fire collars and extra fire safety around windows and doors.