Guernsey’s growing enthusiasm for energy efficiency and renewables

November 5th, 2012 by Richard Lord

Guernsey is improving energy efficiency and developing micro-renewable energy projects but progress is very slow compared to developments in the rest of Europe.

Some Guernsey residents are making their homes more energy efficient and producing and using their own renewable energy.

Guernsey Electricity Ltd increased the price of electricity on 1 October 2012 because of a number of extenuating circumstances, which were precipitated by failure of the electricity cable between Jersey and Guernsey, and failure of another cable between Jersey and France.

The price of photovoltaic panels has declined during the last few years.

Some Guernsey residents are taking advantage of this reality.

A couple living in a St Peter Port townhouse has steadily improved the energy efficiency of their home and added energy efficient heat pumps, and photovoltaic panels to produce electricity.

To improve the energy efficiency of their home, they lined three exterior walls of a house extension with thermal board, applied secondary glazing to their single glazed windows, and added more loft insulation.

Sensible Home Technology installed low wattage LEDs throughout their home, which dramatically reduced the amount of electricity used for lighting, and also provided individual remote control of the lights.

E-Si were employed to install two-14 kW rated Mitsubishi air to water heat pumps to provide heat to an old radiator system, some new underfloor heating, and to provide hot water.

E-Si have developed techniques to overcome some of the issues of working with an old radiator system and been able to reduce the cost of heat pump installation in this kind of home as a consequence.

These quiet heat pumps use latent heat from the outside air, which causes a refrigerant in the system to evaporate. The vapour reaches a high temperature and pressure in a compressor. The hot vapour enters a condenser where it releases large amounts of heat as it condenses. This heat warms the radiators to between 35°C and 45°C, and heats water to over 50°C for bathing and washing. The refrigerant moves to an expansion valve, drops in temperature and pressure, and returns to the evaporator to complete the cycle.

These ‘modulating’ air to water heat pumps work effectively down to an outdoor air temperature of -25°C. They vary their output according to the outdoor and indoor temperature. Even at that outdoor air temperature the air contains latent heat. The air to water heat pump can deliver about 4 kW of heat inside the house for every 1 kW of electricity.

The central heating and the hot water for the property were heated by oil. The oil tank is about to be removed as its last use was to heat an AGA cooker, which was recently removed. An electric AGA cooker is taking its place.

E-Si recently added 22 photovoltaic panels to the main east-facing pitched roof. The panels capture diffuse or direct sunlight to generate electricity even on overcast days. These solar panels will help power the air to water heat pumps.

The performance of the photovoltaic panels on this house can be monitored by the owner using the enecsys monitor, which can be accessed from anywhere in the world via the internet. The solar inverters also ‘modulate’, which increases efficiency of the panels, as shadows fall on the panels during the course of the day.

Guernsey residents who produce electricity for the grid with micro-renewable energy technologies receive payment from the Guernsey Electricity Ltd ‘Buy Back tariff”  which equates with Guernsey Electricity Ltd.’s marginal cost of producing one kWh of electricity (as of 1 October 2012 the buy-back tariff is £09.8930 per kWh).

This is less, on average, than the home owner pays for electricity from the grid, so home owners receive the greatest financial benefit from using the electricity their micro-renewable energy technologies produce in place of the more expensive grid electricity.

E-Si are in the progress of adding another 18 photovoltaic panels to the other east facing roof of the property.

Living in an energy efficient Guernsey home is increasingly attractive as the cost of energy rises.

A growing number of people are attracted to the idea of small energy bills, and are enthusiastic that they are reducing their carbon emissions at the same time.


4 Responses to “Guernsey’s growing enthusiasm for energy efficiency and renewables”

  1. Devil's Advocate

    Is the 14kW rating of the heat pumps the heat output, or the electricity input?

  2. Richard Lord

    The Mitsubishi air to water heat pumps have a rated heating capacity of 14 kW.

  3. Paul Fletcher

    The Energy output of the two heat pumps varies between 10kW and 28kW, the energy input varies between 2.5 and 7kW with an average COP of 4. On a basic winter day, the heat pumps will be just turning over and the 9kW PVs just generating a few kilowatts thus ensuring that during the day the energy for heating is taken care of.

  4. Alex Duncan

    Lovely solution for millionaires, and whats on offer for the rest of us?

Have your say