Retrofit and Sustainability

Yabsley Stevens Architects offer a standalone retrofit and sustainability service for clients who are seeking to improve their buildings’ sustainability credentials. Committed to designing sustainable buildings for more than 25 years, YSA have embedded sustainable thinking into all aspects of our architectural services.

In 2014 emissions from buildings accounted for 34% of the UK’s total greenhouse gas emissions. With 14% of these emissions coming from the UK’s 29m existing homes, retrofitting residential properties is essential to achieve net zero. The government has responded to the climate emergency by committing to net zero emissions by 2050 and setting ever more demanding construction regulations.

Serra Clappa wheel

Sustainable  Living – Serra-de Clappa, Majorca

The requirement for a sustainable home was the driver for the form and appearance of this new house on the outskirts of Arta, a small town near the Northeast coast of Majorca.

The building is dominated by an inverted roof, designed to collect rainwater that is channelled down through the house and stored in an underground cisterna; a traditional method to store water. The roof also provides shade to the flat roof terraced area and helps to reduce the amount of radiant heat absorbed into the building fabric.

A stair tower acts as a visual anchor on the main entrance elevation but is also an integral part of the ventilation strategy. The tower is conceived as a badgir, a wind catcher, a traditional method of cooling air developed in Iran and across the Gulf states. The breeze is funnelled down through the centre of the house, the air cooled in the tower by a central section of the tower being kept wet to cool air via evaporation.

The thick external walls of the ground floor are constructed from solid masonry and faced in stone sourced from the site; this heavyweight construction provides a high thermal mass reducing heat gain through the building fabric keeping the bedrooms cool during the heat of the day. A combination of fixed and moving timber slatted shutters to the first floor living spaces, provide shade and the open slats allow the breeze to enter the space. The moving shutters also enable the view to be fully revealed at times when shade is not required.

Higher EPC requirements

All newly rented properties in the UK must have an enhanced energy performance certificate (EPC) rating of at least C by 2025, and existing tenancies by 2028. All rented commercial properties must have an EPC rating of at least B by 2030. Currently 74% of UK offices are rated below B.

For newbuild homes, compliance with the Future Homes Standards (FHS) will become mandatory in 2025. The government has also announced a consultation on higher performance targets for non-domestic buildings which mean they will be required to be zero carbon ready by 2025. In some instances, building owners are requiring a NABERS rating exceeding regulatory requirement in the UK.

YSA can advise building owners on how best to meet or exceed these new regulations. Working with Interface Facade Engineering (headed by YSA director William Stevens) and in collaboration with other specialists, we can evaluate your existing building, appraise the current building fabric, heating and ventilation systems and recommend the best approach to meet these new targets. Maintaining and enhancing your property value and optimising running costs, along with improving general wellbeing, makes for happier and healthier spaces.

Oak House exterior view from a distance
Oak House exterior view from a distance

Prioritising the response

To enable informed decisions on the most advantageous low energy systems to employ and to optimise resourcing, the strategy to decarbonise buildings must be data driven.

YSA take a fabric-first approach to minimise energy demand. We survey the existing building and assess the U values for each element. Thermal bridges at building junctions are identified and the airtightness of the building estimated.

YSA can then identify the optimal areas to insulate and prioritise elements if budget is a constraint. In conjunction with upgrading the energy efficiency of the building fabric alternative low energy systems can be considered for the heating and ventilation systems along with the installation of solar panels to maximise the contribution from renewables. These measures all contribute to reducing carbon emissions.

Oak House exterior view from a distance
Oak House exterior view from a distance

Fabric-First Upgrade – Camden

A fabric-first approach was taken with the upgrade of a Victorian cottage in a conservation area in Camden. Planning approval was successfully obtained to raise the existing roof and install insulation above it. This was crucial as the first floor already had restricted headroom and insulation could not be accommodated below the existing roof structure.

After checking the detail for interstitial condensation within the roof build-up, the existing slate roof was stripped and insulation added between and above the roof rafters. The roof covering was replaced where necessary with matching reclaimed Welsh slates.

In addition to the roof, the energy efficiency of the external walls was improved, and internal insulation applied to the walls of the first floor bathrooms and ground floor living room. The energy efficiency was further improved with the addition of insulation over the existing solid concrete floor in the living room, enabling underfloor heating to be installed. Underfloor heating is desirable for heating systems as the flow temperature of the water is delivered at a lower temperature which reduces energy demand. 

An air source heat pump was considered for the upgrade however a suitable location was not possible in the tight urban site. A compromise was to replace the existing gas boiler with an energy efficient gas boiler. It is hoped that with advances in technology, and perhaps relaxation in planning regulation for the siting of air source heat pumps, the gas boiler can be replaced with a more energy-efficient solution in future.