Conservation building makes use of three renewable technologies

Project Overview

Peter and Liz Jones wanted to convert two out-buildings - a dovecote and a stable - into dwellings for rental and potentially a home in which to enjoy their retirement. The buildings were untouched since they had been built, over 125 years ago. The conversion into desirable dwellings needed to marry with ease of use and low running costs, with the need to preserve the original character of the buildings.

Viessmann Partner GreenACT was chosen to design, install and commission the heating system and because renewable technologies were chosen to minimise running costs, these also required MCS certification in order to benefit from government scheme tariff payments.

From the outset, Peter and Liz were clear in their wish to use a ground-source heat pump as the means to provide heating and hot water for the new rooms. The key attractions were the very low running costs and the fact that the ground based array could be completely hidden beneath the ground, leaving nothing to detract from the rural setting. In addition, they wanted to take advantage of electricity generated freely on site using solar PV panels, to provide power for the heat pump.

The small garden area was perfect for a vertical probe heat-pump system; two boreholes, each one 86 metres deep, were drilled in just three days. Bringing the heat from the boreholes to the heat pump, which was located at the opposite side of the property, meant taking pre-insulated pipes under the base of the building and up through the floor adjacent to the heat pump.

Since floor space was at a premium, the choice of heat pump was a Viessmann Vitocal 222-G with an output of 7.8 kW. It was an ideal solution because it combines the heat pump with a domestic hot water cylinder in just one unit, about the size of a tall fridge. The heat pump provides sufficient heat to keep the home warm, even at minus 5 degrees Centigrade.

The heat is distributed throughout the home via underfloor heating. Each room is a seperate zone, which can be controlled individually for temperature and timing. This means that rooms only used in the evening can be maintained at a lower temperature when not in use, saving more money through increased efficiency.

Outside, two solar systems were installed on the roof; solar PV to provide free electricity and solar thermal to provide free hot water. The solar PV array consists of 15 panels and over the course of the year, will provide approximately 75% of the electricity required to run the heat pump.

Completing the three renewable technologies, the Viessmann Vitosol 200-T solar thermal system provides 61% of the hot water required for the property. The system uses evacuated tubes, which have been rotated in their housing to orientate as a south facing array from a south facing roof, therefore optimising their output.

All renewable energy systems qualify for the Renewable Heat Incentive or Feed-in Tariff

Statement Viessmann Partner/Operator

Peter Leith from GreenACT Ltd says, "Compared to an oil-fired boiler, which was the conventional alternative, this ground source heating system is saving 40% of energy costs for Peter and Liz every month".


Vitocal 222-G Ground Source Heat Pump

Vitosol 200-T Solar Thermal Array

15 x Solar PV panels 

Rated Output: Ground Source Heat Pump 7.8 kW