Eco-friendly family home becomes benchmark for energy efficient design

Project Overview

Mr and Mrs Terry wanted to build a comfortable home with minimal energy consumption. The project, overseen by Passive House architects and regular collaborative partner of Viessmann’s, bere:architects, was to become the first certified Passivhaus in London and a benchmark for comfortable, energy efficient family housing.

The house requires hardly any heating or cooling thanks to advanced materials and techniques used in its construction. With only 23.6 kg of CO2 per year (including unregulated emissions), carbon emissions from the energy used for the Passivhaus are significantly less than the average UK property today.

Considered design

Families, especially those with young children, demand a lot from their homes. With energy costs steadily increasing at their former property, the Terry family was keen to save as much as possible through minimal energy consumption, when it came to developing their new home.

Architect and consultancy firm, bere:architects, was enlisted from the very beginning of the project. It was decided that solar energy should play a significant part in the hot water system, yet, set in a built-up area of London, the over-shadowing from adjacent buildings was an important consideration. As well as determining the best position for the property, bere:architects used the Passivhaus Planning Package (PHPP) to develop an efficient building envelope. By adhering to the Passivhaus design standard, the property would be erected using advanced low energy construction, so as to be cool in summer and warm in winter.

While water and space heating with fossil fuel would be kept to a minimum, an efficient boiler to support the solar technology was still required as back up for the very coldest, overcast winter days. 

A fully connected system

Led by project architect, Sarah Lewis, bere:architects designed and specified a hot water system for the property in collaboration with low energy services consultant, Alan Clarke, which the main contractor, Visco Ltd, installed. The company fitted 3m² of Viessmann Vitosol 200 T solar thermal tubes to the home’s roof to supply hot water to the ensuite, family bathroom and kitchen. The system works together with a Vitodens 343-F solar DHW storage gas boiler, and is managed via the Vitotronic 200 control unit on the boiler. 

With an integral, 250 litre DHW cylinder, the Vitodens 343-F is able to cater for all of the property’s hot water and space heating needs, from one compact unit. A solar coil fitted inside the cylinder pre-heats water before use.

The boiler provides additional energy through a highly efficient heat exchanger, acting also as an additional source of space heat when required, by delivering top-up heat energy to the air being supplied through a highly efficient PAUL heat recovery ventilation system
and two small towel radiators located in the property’s bathrooms.

Warmth in the harshest of climates

Carbon emissions in the Terry’s home are now just 23.6 kg per year, far less than the five tonnes produced by the average UK household. Energy from Viessmann’s solar thermal technology recently covered more than 90 per cent of the hot water demand during Spring 2015.

“In an age when fuel bills are rising, savings like these make a real difference to our customers,” says Lewis.

“Thanks to Passivhaus design, the property already uses very little heating, even when it’s subzero outside. But hot water is something which is always required, and the efficiency of Viessmann’s products means that energy savings can still be made when condensing
technology is in use.”

Commenting on the property on a cold winter’s day, Mr Terry says, “It’s absolutely beautifully warm in here and zero degrees outside. And it’s always got that lovely sort of ambiance in here, it feels really warm and comfortable and fresh.”

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