Coastal home now produces more electricity than it uses

Project Overview

When one family built an environmentally-friendly energy efficient home from scratch, having a knowledgeable heating company on board was essential – and over time helped to reduce energy usage to a fifth of the national average. With the help of technology designed by Viessmann, the three bedroom house in West Wales not only has a comfortable ambient temperature all year round, but it also produces slightly more electricity than it uses over a year.

The Solution

Charles Redgrove and his family started to construct their coastal home in 1996 following advice and a specification from the Centre for Alternative Technology in Machynlleth. Their dream was for a home that used recycled materials and prevented the heat it produced from escaping. The plans included underfloor heating downstairs which was initially fuelled by an 18kW Viessmann LPG  gas condensing boiler.

After 12 successful years with the LPG boiler, the family decided to change to a cleaner form of heating technology, when heat pumps became more widely available. They installed a Viessmann Vitocal 300-A air source heat pump with a 300 litre cylinder and added  Vitosol 300-T  heat pipe solar thermal tubes on the roof. Using he hole in the roof for the boiler flue to bring in the system pipes from the 30-T made the retrofit simple. To check how efficient their house is, the Redgrove’s log their energy performance every month. The coefficient of performance (COP) of the Vitocal 300-A heat pump is 4.8, so it provides 4.8 units of heat for every one unit of electricity used.

The new system, fitted by Viessmann trained installer Richard Hill of Intelligent Energy Ltd, included Vitovolt 200 photovoltaic panels and has proven extremely successful. While the average family uses 19,800 combined kWh of gas and electricity a year according to the Ofgem website, the Redgrove’s used 10,000 kWh while they had the boiler, but now use less than 3,000 kWh of electricity for everything except cooking, which is still done with LPG. Solar panels have also ensured their heating is carbon neutral, generating more energy than they use in a year. The return from the Feed-in-Tariff is more than the energy costs and provides a financial return on the investment.

Mr Redgrove said “We were looking for the best technology we could afford. We considered oil and gas, but although oil was cheaper at the time, we wanted to use something that was cleaner at the point of burning. We needed a gas condensing boiler that was as efficient as possible and would run on LPG, not an easy item to find in 1996. Viessmann manufactured the only available 96% efficient boiler on the market. They also provided excellent back-up advice and service”.

“There’s underfloor heating downstairs and no heat source upstairs, but the walls, windows and roof are heavily insulated. Viessmann systems are weather compensated, monitoring the outside temperature in order to regulate when to come on. We have an ambient temperature of 20 degrees centigrade all year round downstairs and in the winter, the bedrooms can drop as low as to 16-17 degrees”.