NB: Please read this in conjunction with ‘INTERNAL FABRIC’. Overlaps and boundary issues are inevitable!
See References and Sources for acknowledgements of information contained. Those marked with an asterisk (*) are available as a hard copy for reference in Newington Library
REDUCING CARBON EMISSIONS
Although traditionally constructed buildings are better at conserving heat than has been assumed, much can be done to improve energy efficiency and reduce fuel consumption.
How might this be done while retaining the character and construction type of our dwellings?
Although listed building consent may be required, this may not be a barrier to appropriate improvements. Assessing what is appropriate, however, may involve seeking suitably qualified advice.
ADOPTING A STEP-BY-STEP APPROACH:
- Begin with proper building maintenance
- Aim for energy efficiency through behavioural change, building systems and fabric upgrades: e.g. Is the building wind and water-tight? Are lighting and heating systems energy efficient? Is added insulation or upgrading of windows needed?
PARTICULAR FEATURES OF TRADITIONALLY BUILT HOUSES
- Installing renewable energy technology raises questions about its siting and design in houses in conservation areas.
- Many older houses were designed with passive ventilation to ensure air flow around the building, dispersing water vapour to prevent excessive moisture and subsequent decay. Ideally thermal improvements should ensure that both the building and its occupants can breathe. Using ‘vapour open’ materials (e.g. mineral wool or wood fibre) for insulation allows the release of humidity.
- Proper and regular maintenance (see separate tile) is a prerequisite to undertaking energy efficiency improvements. If a building is not watertight there is little point in making energy efficiency upgrades, and if dampness or excess moisture is already present such upgrades may cause further moisture and damage. Heat loss through a damp masonry wall is higher than from a dry one.
- Practical, routine maintenance: e.g. regular clearing of gutters staves off decay and prevents walls becoming wetter and less thermally efficient; keeping windows and doors in good repair reduces heat loss.
‘QUICK WINS’:
- Draught-proofing: improving insulation is only worthwhile if draughts are properly attended to! Consider windows, doors (including letterboxes and keyholes), and floorboards.
- Chimney balloons stop heat loss via flues not in use.
- Add heavy curtains, shutters or secondary glazing (i.e. panes that go inside existing windows).
- Ensure the loft is well insulated, including pipework and the access hatch.
- Lag hot water cylinder; fit thermostatic radiator valves and low-energy light fittings; install a water butt for garden purposes; place water-saving devices in lavatory cisterns.
LARGER PROJECTS
Consider upgrading the heating system (maybe changing to a renewable fuel source). Some work that may be suitable in a modern building can be extremely detrimental to an older one, especially if it inhibits the evaporation of moisture. Unfortunately, this may include items recommended on an energy performance certificate (EPC) because the software inadvertently discriminates against older, c1919, buildings. When contemplating major work to save energy in an old building, therefore, seek the advice of a suitably qualified professional.
ADJUSTING TO SUSTAINABLE LIVING
Please also see ‘Lifestyle and Habits’.
- Sustainable living is about an entire attitude of mind.
- A holistic view takes into account the whole building and how we can improve the way we use it, e.g. throwing on a thick jumper instead of turning up the heating, air dry rather than tumble dry washing, keep central heating at reasonably even temperatures, and turning off electrical appliances and lights. Obtaining materials locally limits transport distances and cuts pollution.
- Human activities, not buildings, consume energy.
REFERENCES AND SOURCES:
Inform Guide: Improving Energy Efficiency in Traditional Buildings (historicenvironment.scot) *
Responsible Retrofit Guidance Tool (responsible-retrofit.org)
STBA Guidance Wheel – STBA (stbauk.org)
Energy Efficiency and Old Buildings: Principles and Priorities | spab.org.uk
Make your home warmer | Home Energy Scotland
Measures to help reduce home heat loss – Energy Saving Trust
ROOFS AND ATTICS
SLOPING ROOFS AND ATTICS
LOFT INSULATION: Approximately 25% of heat is lost through a typical roof.
Many types of insulating materials are available:
- natural materials e.g. hemp fibre boards or sheep’s wool. Natural materials are generally preferable in traditional buildings, because they are better for buffering moisture and preventing condensation.
- recycled products from newspaper, glass and modern materials.
- Insulation placed between the ceiling joists in the conventional way, gives a “cold roof”, or fitted between the rafters, for a “warm roof”.
Cooms: (the sloping parts of the ceiling often found in upper floors or attics) should be effectively insulated whilst at the same time maintaining ventilation throughout the roof space. Current guidance is that there should be a 40mm gap between the top of the insulation and the underside of sarking boards. (Sarking is wood boarding used under tiles or slates in Scotland.) Wood fibre board has proved effective in this context.
FLAT ROOFS
Insulation presents several technical challenges compared with loft insulation. The methods and materials used require careful prior consideration. Traditionally, flat roofs are covered in metal, most commonly lead (although zinc and copper are also used, and more recently tern-coated steel), with bituminous coverings becoming common on post mid-19th century flat roofs.
Insulation is usually placed between the joists holding the sarking (or ‘decking’) in place. This might require removal of all, or part, of the ceiling to allow the fitting of the insulation between joists. A rigid, vapour permeable insulation material can then be installed between the joists and closed in with new linings, either reinstating lath and plaster or using a modern alternative. An alternative method for installation between joists is to remove the roof covering to allow access from above. This is only likely to be practical when the roof covering is to be renewed.
REFERENCES AND SOURCES:
SOLAR PHOTOVOLTAICS
HOW IT WORKS
Solar PV produces electricity when light reaches the semiconductor material and energises the electrons in the solar module, creating a direct current (DC) of electricity. This is then converted to an alternating current (AC) by an inverter to be used in a building’s electrical system. It may also be exported to the National Grid or stored in a battery for later use.
OUTPUT
Many factors can affect the output of a solar PV system including the type of module used, the size of the array (linked collection of solar panels), the orientation of the array to the sun and shading on the modules.
DIFFERENT KINDS AND SITING
Many forms are available, but they are most commonly found as panels, which can be mounted on roofs or on separate frames on the ground, e.g. in gardens, connected to a building by cable.
The ideal siting for solar collectors (in Scotland) is a south-facing, unshaded aspect set at an angle between 30° and 50°. The amount of electricity that is produced depends on the amount of light that falls on the collectors.
Consideration needs also to be given to whether the supporting roof structure can take the additional load e.g. to avoid penetration of a flat roof surface panels are held in place by weighted bags.
REFERENCES AND SOURCES
Short Guide: Micro-Renewables in the Historic Environment | HES *
Renewable energy | Home Energy Scotland
SOLAR THERMAL
HOW IT WORKS
Solar thermal systems make use of the sun’s energy to provide hot water and occasionally space heating. A pump circulates fluid through the solar collector (either a flat panel or a glass tube collector) which heats water in the cylinder via a heat exchanger. This hot water is then circulated through the building for heating or to provide domestic hot water. A back-up boiler system is also connected to the cylinder to provide hot water on days when the panels do not produce enough heat. Commonly, solar thermal systems simply help raise the temperature of the water inside the cylinder so that existing conventional boilers use less energy. To maximise the amount of sunlight the collectors receive, they should face south and be set at an angle of 30°- 50°C.
REFERENCES AND SOURCES
Short Guide: Micro-Renewables in the Historic Environment | HES *
Renewable energy | Home Energy Scotland
CHIMNEYS
Chimneys may be able to be re-used for new heating appliances e.g. modern enclosed grates, wood burning stoves and biomass micro-renewable systems. In this case, a thorough flue inspection should be carried out and any repairs undertaken to the masonry and the lining; the chimney may also need to be re-lined. Professional advice should be sought in all cases.
REFERENCES AND SOURCES
EXTERNAL WALLS
EXTERNAL INSULATION
Insulating material can sometimes be applied to the external face of the masonry. Due to aesthetic considerations and difficulties in application, this approach is unlikely to be appropriate to many traditionally constructed buildings, e.g. where there is high quality ashlar work or a visually attractive façade. However, where a building has been rendered, or on a rear extension, the application of an insulated replacement could be considered, especially where the render is an inappropriate cement based material, the removal of which would help both the health of the building and its thermal performance.
When considering external insulation it is important to use a material which is appropriate. Boards and spray applied material which does not allow a degree of moisture movement through the structure should not be used as the long term effects are still to be assessed, and invariably require the formation of complex junctions between the new wall plane and existing details such as eaves, rhones and downpipes.
REFERENCES AND SOURCES
Inform Guide: Improving Energy Efficiency in Traditional Buildings *
Advice on insulating your solid walls – Energy Saving Trust
WINDOWS – SECONDARY / DOUBLE / TRIPLE GLAZING
See also ‘Planning’ tile
INTRODUCTION
A single pane of glass has a fairly poor thermal performance, but several sensitive upgrade options could considerably improve this. E.g. draft stripping the sashes can reduce air leakage by 80%, as well as allowing the full use of the window in terms of opening and closing, although it will not improve the U-value or thermal transmittance. (The better-insulated a structure is, the lower the U-value will be). Many companies provide this service, combining the upgrading work with a general overhaul of the window and the sash cords.
Many thermal improvements can be made to a window without changing its fabric:
SECONDARY GLAZING
Tests show this is the most effective option, reducing heat loss through the window by 63%. It now comes in a variety of different styles and techniques.
TIMBER SHUTTERS
Shutters are the most effective option of the traditional methods, reducing heat loss by 51%. A combination of measures provides the greatest reductions in heat loss. i.e. secondary glazing, or combinations of heavy curtains and shutters.
DOUBLE GLAZING
A range of double glazed units can be retrofitted into existing sash and case windows to greatly improve energy efficiency without adversely altering the character of the window. Before carrying out any work, planning regulations may require that the historic significance of existing glazing is considered. Improved glass comes in the form of slim profile double glazing, or more advanced products involving vacuum panes. While sash and case windows are extremely durable, and when well-maintained will last many years, if extensive repair or replacement of windows is necessary, modern glazing options may be considered. Not all options are appropriate in all cases, but there will always be a combination of measures suitable to improve the thermal performance of windows in traditional buildings.
REFERENCES AND SOURCES
Inform Guide: Improving Energy Efficiency in Traditional Buildings *
Retrofitting Historic Sash & Case Windows: A Quick Start Guide for Homeowners
EXTERNAL DOORS
Frames of traditional timber doors generally perform well thermally. Improvement can often be made to the panels (typically made of thinner wood) by adding a layer of appropriate thin insulation material on the inside of the door panel, thus maintaining the character of the door from the outside. Due to their higher performance than conventional products, such materials can be expensive, but in small areas allow the sensitive upgrade of an otherwise sound door. In all cases the finished insulation should be kept flush with the door framework; new beads may be required to finish the edge. Draught or weather stripping around the edge of the door and the letter box can also help.
REFERENCES AND SOURCES
Inform Guide: Improving Energy Efficiency in Traditional Buildings *