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Social housing supplement Retrofi t

Competition to kick-start upgrade revolution

‘Retrofi t for the Future’ was conceived as a competition that would kick-start the revolution needed in social housing upgrades. Specifi cally focusing on street properties, it sets an ambitious target for reducing CO2 emissions, aiming for an 80 per cent cut compared to the average UK dwelling in 1990. The actual fi gure was set at 17 kg/ sq m/yr, with a further target for primary energy consumption of 115 kWh/sq m/yr. These targets assumed modelling with SAP 2005

but using a competition-specifi c extension sheet that could accommodate 100 per cent low-energy lighting and a limited range of appliances. From around 380 original bids, 86 projects across the UK were awarded funding earlier this year from the Technology Strategy Board (TSB) at an average of £142,000 to implement a package of innovative retrofi t measures on their selected property. The TSB’s intention is that a ‘pattern book’ of

retrofi t solutions will emerge from the Retrofi t for the Future competition. The TSB was set up to help stimulate innovation.

“Our aim is to determine whether the heat-led co-generation is a viable low carbon measure”

the limits on thermal performance created by the conservation guidelines lead to a space heating demand that remains relatively high, at around 75 kWh/sq m/ yr. This is more than three times the modelled demand for the Mottingham house but is a reflection of the compromises that have to be made in properties with heritage value. The need for an easily replicable, effi cient form of heating therefore remains and for this project, micro-CHP was the preferred technology. The Baxi Ecogen unit uses a free-piston Stirling

A whole-house heat recovery system provides fresh, fi ltered air extracted from the kitchen and bathroom.

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will be more thorough, aiming to at least better a rate of 3.0 cu m/h. The strategy incorporates the continuous layer of lime plaster for the bulk of the walls but will employ a specialist range of tapes and grommets at all junctions with windows and service penetrations. A whole-house heat recovery mechanical ventilation system from EnviroVent will then provide pre-warmed, fi ltered, fresh air by recovering almost all the heat from the air extracted from the kitchen and bathroom. The features of the Energivent Q address some of

the shortcomings of our previous installation, with vapour tracking controls and inlet valves; intelligent, energy saving zone controls; DC motors; a wireless remote user interface; fi ve-year fi lters; and a SAP Q approved, modular design that is ideal for retrofit as it allows greater ease of installation. Despite the measures specified above, three external walls and

16

CIBSE Journal June 2010

engine to provide up to 6kW of thermal output for space heating and hot water while generating up to 1kW of electricity per hour that can be used in the home. Baxi suggests that field trials and laboratory testing have indicated savings of one tonne of CO2 per year. Our aim is to determine whether the heat-led co-generation is a viable low carbon measure, particularly where thermal upgrade is limited and roof-mounted solar thermal collectors are not possible for planning reasons. To improve the micro-CHP’s effi ciency further, we

are introducing a Wattbox controller, a newly developed control system that monitors electrical consumption to learn residents’ occupancy patterns. The controller then ensures that internal temperatures and hot water heating are fi ne-tuned to both match demand and optimise electrical output, without the need to set complicated programmes. The only user interface is a

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