Older buildings are better at retaining heat than has been suggested by standard computer energy-efficiency models, as these are based on the presumption of modern building methods and materials. ‘In some cases, heat loss through vernacular materials can be up to three times lower than expected,’ says Roger Hunt, co-author of the Old House Handbook.
Old buildings are intended to breathe, thus preventing, for example, moisture building up around timbers, which can happen if you block eaves space. Solid walls deal with damp differently from modern cavity walls, so ensure that any damp-proofing work recognises this factor. In solid-wall buildings, the exterior was designed to absorb moisture, which evaporates naturally later. Certain renders, paints, sealants and membranes can prevent the building from functioning naturally. Loft-insulation materials that allow breathability include sheep wool, hemp quilts, wood fibre and several types of cellulose materials.
The price comparison site Compare My Solar says that the average price of domestic solar-power installation fell by 30% last year, and the site’s founder, Gertjan van der Goot, expects further price reductions in 2012, which, he says, means that ‘the financial return can be more than 10% for an installation on a south-facing roof’. But to get permission for solar panels on a listed building the panels need to be hidden. ‘Georgian houses often have a parapet and a central box gutter that is ideal for this,’ advises Mark Stimpson of Green Sky Architecture. Alternatively, you could try solar slates similar to those that have been installed at Grade II-listed Maslan Farm in Wiltshire, where 140 solar slates on the roof provide renewable electricity. ‘Installing 154 solar slates covers about 26 sq ft of roof area and would cost about £6,400, explains Solar Slate’s Gavin McAlpine. ‘This would generate about 30% of the energy expen-diture of the average UK house.’
Conservation officers are reluctant to allow double-glazed replacement windows, as the depth of window is greater than what went before and so alters the external look of the property. However, you can buy especially thin double-glazed windows, which can be acceptable in some circumstances, as can secondary glazing. If replacing glass, ‘specify high g-value glazing to south-facing windows to increase the amount of solar gain,’ recommends Mr Stimpson.
However, Dr Simon Thurley, the chief executive of English Heritage, believes ‘many original timber sash windows have lasted more than 200 years, and it’s a waste to throw them away’. English Heritage say tests on air infiltration through sash windows show this can be reduced by up to 86% by adding draught proofing, and simply closing thick curtains and roller blinds can reduce heat loss
by 41% and 38% respectively.
Mr Hunt recommends filling draughty gaps between floorboards with string: ‘Measure the thickness you need, stain the string the right colour, and poke it into the gap with a screwdriver and fix with woodwork glue.’ If floorboards need to be replaced, consider bamboo rather than wooden ones-bamboo is hardwearing and a highly renewable source as it grows so quickly.
Biomass heating systems burn renewable energy sources such as wood pellets, chips or logs, which are cheaper energy sources than oil or electricity. David Hugh-Smith installed a biomass heating system in his early-Georgian, listed manor house, and liked it so much that he bought into the company that installed it, Dunster Forest Energy. His system cost £90,000 to install, and has reduced his energy expenditure from £15,000 a year to £5,000. He also ‘expects to join the Renewable Heat Incentive (RHI) scheme, which will generate an index-linked 20-year income starting at £13,500 per annum’.
To qualify for RHI grants there has to be more than one property Mr Hugh-Smith’s manor house has two farmhouses. For those who do qualify, Dunster Forest Energy offer an option whereby the installation is paid for by an investor who then receives the RHI payments and undertakes repairs and servicing. The customer pays for the fuel. This autumn, the Government will launch ‘The Green Deal’, making energy-saving improvements more affordable for rural homeowners.
For details, visit www.decc.gov.uk
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