Retrofitting Historic Buildings - Westminster City Council

Solar thermal panels use the radiant heat of the sun to warmwater in solar collectors which is pumped to a thermal store.It is most likely to be used to top up or supplement a mainsystem, rather than meet all of a building’s water heatingdemand. It is well suited to domestic buildings which have ademand for hot water. The minimum amount of space needed tobe effective is around 2-4m 2 , ideally between south east andsouth west facing, at an angle of 30˚ and should not be shadedby trees or neighbouring buildings. In addition to the collectorpanels, space is typically needed to house a large hot-watercylinder with a storage capacity of at least 120 litres, and up to200-300 litres for larger buildings. Additional pipework will alsobe necessary.There are different types of system, direct and indirect. Directsystems heat potable water in the collector panel, and pump it toa tank for use. Indirect systems are filled with fluid (oftenantifreeze) which passes through the collector panel and a heatexchanger transfers heat to potable water which is separate fromthe fluid circulating in the panels. This slightly more complexsystem provides freeze and overheating protection.For many properties this will be permitted development and willnot require planning permission, although if you live in a listedbuilding, this is not the case.CostsSolarThermalPanelsPhotovoltaic(PV)electricpanels 65UnitPeraveragedomesticsystemCost(lower)Cost(Upper)Cost(average)Subsidies (refer toEST website forlatest info 64£4500 £5500 £5000 Renewable HeatIncentiveWhen to do this: For buildings which have an appropriate southfacing roof slope the renewable heat incentive, will offer asubsidy making this more financially attractive and reducing thepayback period.For further information see:• ‘An Introduction to Low Carbon Domestic Refurbishment’Construction Products Association (2010)http://www.constructionproducts.org.uk/publications/dbfiles/Domestic%20Refurbishment%20Revised11010%20(low%20res).pdf51