ENERGY EFFICIENT HOUSING DEMAND CONTROLLED VENTILATION


Demand controlled ventilation allows air to be circulated according to a building’s use and occupancy. Its omission from SAP should be quickly rectified, challenges heating and ventilation consultant Dr Chris Irwin


E www.cibsejournal.com


mphasis on the Standard Assessment Procedure (SAP) by housebuilders seeking the most energy efficient method of


ventilation is leading to a situation where mechanical extract ventilation (MEV) and mechanical ventilation with heat recovery (MVHR) are perceived as the only systems that can ventilate airtight homes adequately and still meet target emission rates (TERs). We are only four years away from the government target to make all new housing carbon neutral, but demand controlled


ventilation (DCV), arguably the most effective energy saving ventilation innovation proven to reduce emissions and slash running costs, is left to languish on the sidelines of new build projects because the Code for Sustainable Homes (which DCV satisfies completely) is so tightly tied to SAP. SAP is only applied to ‘recognised technologies’ such as MEV and MVHR – the ‘key’ indicators of energy efficiency measured under SAP being specific fan power (SFP) and heat recovery efficiency through the heat exchanger. DCV uses sensors to monitor and measure ambient conditions and feed real-time data back to the zone controller. This adjusts the fan speed modulating the ventilation rate to match the use and occupancy of the building.


September 2012 CIBSE Journal 45


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