Project Overview:
Background:
This residential refurbishment, delivered to the EnerPHIT standard, was named a finalist in the ‘Small Projects’ category of the 2021 UK Passivhaus Awards.
The scheme was delivered in 2019, to a design by Chartered Architect and registered RIBA Client Adviser, Ruth Butler. It entailed making a range of energy efficiency improvements to a detached private home in Barton-on-Sea in Hampshire, which was built in the 1930s and featured brick cavity walls and a tiled roof.
The intention was to achieve the certified EnerPHit standard while retaining the existing walls, roof and floor.
The Brief:
The project was multifaceted. Important modifications included a remodelling of the interior to optimise the use of natural daylight, the creation of a new insulated timber floor, and the installation of triple glazed windows and doors. It also demanded extensive insulation throughout, part of which included the installation of an insulated render system. For this element, PermaRock was selected as the supplier and designer.
Design and Specification:
The chosen EWI system comprised:
PermaRock EPS-Premium is a high-performance, lightweight external wall insulation system based on expanded polystyrene (EPS) insulating panels. The panels incorporate a graphite additive, which gives the insulation improved thermal performance over standard (white) EPS. The system may be installed in thicknesses up to 300 mm and enables very low U-values to be achieved.
It has zero Ozone Depletion Potential and low Global Warming Potential. It enables extremely airtight façades to be maintained and is frequently specified for use on Passivhaus and EnerPHit projects.
PermaRock SiliconeUltra K Finish is a through-coloured, nano-quartz, textured render that is lightweight and water repellent, and which exhibits excellent water vapour permeability. It is available in a wide range of colours and effectively resists the accumulation of dirt, mould and algae, so it tends to retain its bright, clean appearance. For this scheme, two colours were chosen: Bright White and Granit 25 (grey).
Result:
The work was completed in 2019 and demonstrated the effectiveness of deep retrofit schemes. An analysis of the home’s embodied carbon (using PHribbon) estimated emissions to be less than half of an equivalent new-build Passivhaus project.
As noted in a Passivhaus Trust case study, once the major modifications were complete, contractors removed the original heating system, which was replaced by a single radiator and the use of PV panels for solar energy and hot water. M&E services were carefully designed and incorporated within the building to minimise the need for penetrations and, thus, to maximise airtightness.
The architect reported that, after the installation of the EWI system, the U-value of the insulated brick cavity wall fell to 0.267 W/(m2K).
In a similar vein, the client reported that: “The result has been well worth the effort. Our home is now using only a third of the energy and is much more comfortable, in all weathers.”
More information can also be found on the Ruth Butler (RIBA Architect) website.
Photo credit: Peter Langdon Photography.