The Building Conservation Directory 2024

22 THE BUILDING CONSERVATION DIRECTORY 2024 CATHEDRAL COMMUNICATIONS RETROFIT Passive and active strategies for upgrading energy performance while holding embodied carbon MARTINA PACIFICI WE KNOW that, compared with other countries in Europe, the UK’s building stock is in a sorry state; old, thermally inefficient and run down. Data from a study by German company tado GmbH, based on a survey of 80,000 homes across Europe, shows that UK homes lose up to three times more heat and lose it faster than their European neighbours. For example, the average UK home loses three degrees after a period of five hours with a temperature of 20 degrees inside and zero degrees outside. Conversely, a Norwegian home will lose 0.9 degrees over the same period. Basically, in winter British heating systems need to work much harder and use more fuel to keep temperature constant. That’s because the UK has some of the oldest housing stock compared to EU member states. Approximately 38 per cent of UK homes were built pre-1946 compared to 24 per cent for Germany and Sweden, and these homes won’t perform any better without some degree of intervention by way of retrofitting. This is the preferred approach to avoid the release into the atmosphere of the embodied carbon locked within ageing building stock. A major stepup is required for many dwellings to move from existing high energy demand levels to a performance level that matches our European neighbours. UK buildings are also responsible for approximately 18 per cent of the UK’s greenhouse gas emissions through their use of oil and gas for heating and hot water. These emissions need to be cut significantly by 2030 to help meet legally binding climate goals. According to scientific studies, we need a reduction of seven per cent on our current emission rate to hit climate change targets. However, during Covid and a period when travel and other emissions sources were significantly reduced, we achieved a reduction of only six per cent. We therefore need major change if we want to shift the dial to where it needs to be. In the UK, 80 per cent of the homes that we will be using in 2050 have already been built but our new-build standards are not yet aligned to net zero, so homes we are building now will need to be retrofitted before 2050. Retrofit approaches may vary a lot depending on the building’s age. Older buildings (broadly pre-1919) require different understanding, skills and material solutions to allow for improvement. This is due to the challenges posed by their peculiar building physics, which are different from those in houses of more modern construction. Most modern buildings depend on impermeable barriers to control the movement of moisture and air through the building fabric, but older traditional buildings tend to absorb moisture from their surroundings and release it depending on environmental conditions. Buildings of traditional construction have greater ‘thermal inertia’ than their more modern counterparts, heating up and cooling down more slowly, and this ability to ‘buffer’ moisture and heat can help to even out fluctuations in humidity and temperature. LISTED AND HISTORIC PROPERTIES Listed and historic properties are special, not least because they have additional significance and are of exceptional interest in a social and heritage context. Despite these sensitivities, many are family homes with their occupants requiring comfort, heat, light and a clean, healthy environment while also ensuring that the historic character of their property is maintained. This security of tradition is important but it means that we have to find ways to make these buildings not just energy efficient and fit for comfortable living, but also able to secure their embodied carbon footprint, while of course respecting the important heritage and significance the listing recognises. This is a balance that is sometimes difficult to achieve. However, replacement or repair of old systems, or the introduction of new systems to improve safety, comfort and energy performance still have implications in terms of their embodied and operational carbon footprint. They should be calculated and steps taken to minimise them as much as possible. WHAT OPTIONS ARE THERE TO IMPROVE THE ENERGY PERFORMANCE OF TRADITIONAL AND HISTORIC BUILDINGS? Extensions and most alterations to the exterior of a building require planning permission. Houses are allowed a little more freedom and can carry out small alterations under ‘permitted development’ rights, but these can be removed by the local authority where the building is in a conservation area. A building might, for example, require a planning application to change the windows or to add an insulated render. Where a building is protected as a listed building, local authority consent is needed for all alterations, including any alterations to the building, inside and out, which might affect its significance (see page 11). Looking at energy efficiency measures for listed properties, we must consider what Retrofitting a Grade II listed building in the Cotswolds (All photos: Adam Architecture)