Systems from Total Home Environment have exceeded Passivhaus requirements after being invited three years ago, to provide ventilation, space heating and hot water in three of the most thermally efficient houses in the UK.
After a few years of severe winters, results from the houses in Chewton Mendip, Somerset, show that the mechanical heat ventilation with heat recovery system (MVHR) has surpassed Passivhaus requirements. Built by local builder, Arthur Bland, the three properties were designed to meet the zero-carbon rating standards for new houses set by the government for 2016.
With Passivhaus design, in energy terms the requirements are that the primary energy consumed each year for all uses shall not be more than 120kWh for each square metre of floor space. Despite this being an all-electric house, its primary energy use is only 94.2kWh/ m2 per year.
The high level of insulation in the properties meant that a heat recovery ventilation system was needed to introduce fresh air to the buildings without a loss of heat through traditional forms of ventilation as no central heating system had been planned. To meet this challenge, Total Home Environment specified the Genvex Combi 185, which is an all-in-one appliance combining heat recovery ventilation and a heat pump for space heating and domestic hot water. The Combi 185s change the air inside each of the properties once every two hours whilst using a 95% efficient counter-current heat exchanger to recover heat. The integrated exhaust air-source heat pumps further heats each of the homes and their domestic water requirements.
Commenting on the project, Arthur Bland said, “After considering similar systems I chose to specify the Genvex Combi 185 as a single compact appliance with the capacity to accept solar energy if required. The Combi 185 is the best system available in terms of heat recovery – the whole energy bill, including cooking, washing, lighting and entertainment, for the last year for one of the properties was under £500 – I have no doubt that the Genvex has contributed to that huge cost saving.”
The Combi 185 offers priority switching to heat water first in the 185 litre integrated storage cylinder and can be fitted with a bare tube heat exchanger for use with solar heating or a wood-burning boiler. Maximum airflow is 350m³/h and it provides ventilation, space heating and hot water for up to a three people in a 290m² home.
Further information and technical advice on the Genvex system is available from Total Home Environment on 0845 260 0123, email [email protected] or by visiting the company’s website at www.totalhome.co.uk
