Climate change has driven environmental concerns to the top of the agenda in nearly every aspect of our lives. Along the way ‘sustainability’ has become a buzz word.
In this context historic buildings have had rather a bad press; cold, dark, draughty buildings which are inefficient to heat, consume vast amounts of energy and have disproportionate carbon footprints. To sell your house you need an Energy Performance Certificate (EPC) – even after the demise of HIPs. Older, traditional buildings (with solid walls and no damp-proof course) perform notoriously badly in these assessments.
But is this accurate? Or are we suffering from one of our frequent failings: assuming that modern must be better?
What is sustainability?
It is about much more than this month’s heating bill! It is using and managing resources in such a way that the environment is protected for the benefit of future generations.
To understand the sustainability of our domestic property we must think about:
* The energy consumed to live comfortably
* The energy used in a building’s construction – embodied energy
* The source, environmental impact and embodied energy of materials used for maintenance and repair
* The lifetime, future use and disposal of the building and its components
In a series of blogs I’m going to consider each of these factors, so let’s begin with the first:
Let’s deal with the problem issue head on. Poorly insulated, single glazed and draughty historic buildings take a lot of energy to heat. Don’t they?
The answer to this is much more complicated than we are often led to believe. There is actually very little hard information to go on; assessments of energy use tend to be based on theoretical models rather than actual measurements. Several organisations, including English Heritage, Historic Scotland and SPAB, are involved in research to find out the facts behind these assumptions. Some of the initial findings are rather surprising:
* Recent measurements by Historic Scotland have found that a dry wall, bonded with lime mortar can have a thermal performance up to three times better than assumed in an EPC calculation and not much worse than an insulated cavity wall.
* A study of court buildings in England found that traditional buildings had lower energy bills than those from the mid 20th Century.
* Experiments have shown that Tudor, timber-framed houses can sometimes out-perform modern buildings.
* Older terraces are usually easier to keep warm than detached houses, simply because they have fewer walls through which to lose heat.
Traditional, solid walled buildings have a high thermal mass – they absorb heat into the structure when it is warm and slowly release it in cooler weather. This tends to mean they are cooler in summer and warmer in winter. Summer cooling is largely ignored in this discussion, but we are having a hot summer and are being told to expect more. Modern buildings, with almost no natural air movement, need to be mechanically ventilated and cooled.Of course poor insulation and air leakage are common in older buildings. They have an impact on the comfort of occupants and the energy needed to stay warm.The thing is, these problems can generally be fixed without any adverse impact on the character of the building.
25% of heat loss is through the roof. It is usually no more difficult to insulate the roof than for a modern building, so long as the materials used are breathable and ventilation is maintained. Windows and doors can be upgraded rather than replaced. English Heritage have just published research which shows that draughtproofing, secondary glazing and shutters can improve the thermal performance of sash windows by 80-90%, bringing them within the requirements of modern building regulations.
Insulation of floors and walls is also often possible, especially during the course of conservation or refurbishment work. It can be complicated to do this while safeguarding the performance and character of the building, so specialist advice will always be needed.
Much of this work will require Listed Building Consent, Conservation Area Consent and Building Regulations approval. It is important that the historic character of the building is protected. To get the best result for both building and occupants, a carefully planned, holistic approach is always most successful.
If that’s starting to sound rather intimidating, it needn’t be. Experience and understanding of historic buildings and the procedures involved makes life a lot easier. Expert advice and guidance can save a lot of hassle, ensure a better result and, very happily, minimise expense.
Alan Tierney is a historic building consultant. He runs Picketts Historic Building Conservation, advising clients on all aspects of the care, maintenance and alteration of historic buildings.
Picketts Historic Building Conservation is a member of ProjectBook, which has been created to help owners of listed or period properties understand how their buildings work and to help them find appropriate craftsmen, products and specialist information. The online Heritage Register contains over 540 registered businesses, the largest directory of its type in the UK. For more information, visit www.projectbook.co.uk.
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