Energy efficiency and traditional buildings
How Energy is Lost from Buildings
In order to understand how to conserve energy in buildings it is necessary to understand how and where energy is lost from buildings.
- Walls: The majority of heat loss from a building occurs through the walls, as the largest surface area. This is dependent on building material, wall construction and level of insulation.
- Roof: Approximately 25% of heat loss from a building is through the roof. This is dependent on roofing construction, roofing material and insulation.
- Windows: Between 10-20% of energy loss from a building is through windows. This is dependent on type, material, draught-proofing and glazing.
- Doors: Approximately 15% of energy loss from a building is through doors, as a large opening.
The Differences between Modern and Traditional Buildings
Historic England guidance advises that when considering improvements for energy conservation it is important to remember that traditional (historic) buildings, which can include Listed Buildings, perform very differently from modern buildings. Historic England defines traditional buildings as those likely to have been built before 1919, those with a solid-wall construction, those with no damp-proof course and those with bay or sash windows, single-glazed.
Source: English Heritage, Energy Conservation in Traditional Buildings, pg. 4
The fabric of traditional buildings needs to ‘breath’, to release and absorb moisture from, for example, rising damp, rain, and condensation. Traditional buildings require approximately twice the amount of ventilation of modern buildings; moisture moves through traditional buildings until it evaporates. Modern, impermeable building products obstruct this process with the aim of keeping moisture out, which works in modern buildings specifically designed to keep moisture out, but is damaging in traditional buildings that require higher levels of ventilation.
The introduction of modern materials and methods (such as uPVC and double-glazing) in traditional buildings is counter-productive because they restrict air flow, trapping moisture inside, accelerating decay.
Methods of Energy Conservation
The methods below are provided in order of least intrusive, and therefore most appropriate, in traditional buildings, particularly Listed Buildings, with the first being the least intrusive and the last being the most intrusive.
1. Energy Efficient Products: Changing incandescent lamps to energy efficient versions will save energy and is a quick and cheap solution, as is purchasing energy efficient white goods. Such products would not require prior Listed Building Consent.
2. Loft Insulation: Improving insulation in lofts and attics below pitched roofs is one of the easiest and cheapest ways of improving a building’s energy efficiency. In traditional buildings natural insulation materials, such as sheep’s wool and hemp fibre, are better than modern materials, such as fibreglass and mineral wool, because the latter have a tendency to hold moisture, which can increase the risk of damp, timber decay and mould growth. Loft insulation is unlikely to require prior Listed Building Consent. Pipework and hot-water cylinders can also benefit from insulation and would not require prior Listed Building Consent.
3. Boilers: They account for around 60% of all domestic CO2 emissions, so using an energy efficient boiler will cut your home’s CO2 emissions and save money. In Listing Buildings a new location and / or piping for a new boiler is likely to require prior Listed Building Consent. However, replacing an old boiler with a new boiler in the same location and same piping may not require prior Listed Building Consent.
4. Draught-Proofing: Traditional buildings may be over-ventilated and draught-proofing is one of the best and least intrusive ways of improving comfort, reducing heat loss and also reducing noise and dust ingress. Windows, doors, letter boxes, loft hatches and even cat flaps can let cold air in, so can all be improved by draught-proofing. If carried out carefully, many draught-proofing measures are compatible with the principles of building conservation because they are typically reversible with few lasting consequences and no loss of historic fabric. For casement windows the process is simple, with a wide range of products available, including durable rubber seals which are discretely rebated into the window frame. The draught proofing of double hung sash windows is more complex, requiring the replacement of the parting bead with a new component incorporating rubber blades to maintain the seal at the sides, and compression seals to the meeting rail, window head and sill. Draught-proofing may require prior Listed Building Consent, but is a solution welcomed to improve energy conservation in traditional buildings with original or traditional windows. Using existing shutters can also help cut down heat loss through windows.
5. Secondary Glazing: This is an alternative to installing new double-glazed windows because it retains the existing windows and preserves the property’s external appearance, whilst improving energy efficiency. There are many options for secondary glazing including selecting the best method of opening, the use of devices which avoid condensation build-up (such as a one-way trickle ventilator) and even double-glazed secondary glazing, as is widespread practice in northern Europe. Secondary glazing is encouraged in Listed Buildings as an alternative to double-glazing. Secondary glazing is likely to require prior Listed Building Consent, but is a solution welcomed to improve energy conservation in traditional buildings with original or traditional windows.
6. Wall Insulation: Around a third of heat lost in homes is through walls so insulating them will improve a building’s energy conservation. With their solid walls, traditional buildings can potentially be insulated using three methods: external cladding, internal insulation using wall battens and internal lining, sometimes referred to as ‘dry lining’. Wall insulation is likely to require prior Listed Building Consent.
7. Double-Glazing: While it would take many years to get a return on the cost of new windows simply from savings in energy costs, they can improve a home’s overall comfort by reducing draughts. Double-glazing is not encouraged in Listed Buildings because it may involve the loss of the original windows and the introduction of a range of details that can ruin a traditional building’s character and appearance, including thicker glazing bars and beading instead of putty. In a large window with a single glazing bar, the difference will not be as noticeable as in a small-paned sash. Prior Listed Building Consent is required for double-glazed windows and doors.
8. uPVC Windows and Doors: They are damaging to the character, appearance (and can be damaging to the preservation) of traditional buildings:
a. Cost: The sizeable investment needed for replacement windows from timber to uPVC is rarely reflected in the value of the property. Installing such windows in an historic building can in fact reduce its value, as evidenced by English Heritage's survey of estate agents in 2009. uPVC windows are not cheaper in the long run, despite the maintenance-free claims made for them they are vulnerable to heat and UV light and have a life of approximately 25 years. If timber windows are 60 years old or older, it is likely the timber is old growth-dense and durable wood that is now scarce. When they fail uPVC windows cannot be repaired.
b. Damage: old buildings need to 'breathe' so eliminating all draughts can lead to condensation and damp problems in hidden parts of the structure.
c. Ecologically: the use of uPVC is damaging both in terms of the energy needed for manufacture and the problems associated with its disposal.
Visually: the material, frame sizes, mouldings, glazing bars, glass and method of opening will look wrong in an historic building.
Prior Listed Building Consent is required for changes in windows and doors (in materials, glazing and or method of opening) in Listed Buildings. Planning permission is required for the same changes in windows and doors in commercial properties and in flats and may be required for houses in Conservation Areas.
You should check with the Council’s Development Management Section to confirm whether your require prior consent or permission from the Council before undertaking any work. Work carried out without the required consents and / or permissions may result in enforcement action, which will cause disruption and can lead to considerable expense.
Useful Documents and Websites
Energy Saving Trust [external link]
Darlington Partnership, Darlington’s Climate Change Strategy 2006-2010
Historic England, Climate Change and the Historic Environment
Historic England, Energy Conservation in Traditional Buildings