Sample Project - Brook House
As a technology demonstrator we have installed a complete low energy heating and hot water system in a house near Shrewsbury to show just what can be acheived using low energy heat pump systems.
Brook House is a 16th century listed building and as such is a very difficult property to heat and cool.
The house had an existing heating system of fairly conventional design with a combined gas boiler and cooker, an electric water heater supplemented by the boiler and conventional panel radiators.
Any System needed to retain the existing pipework as major stuctoral changes were out of the question.
We needed to find a system that would
- Improve Energy Efficiency in this most ineficient of buildings
- Reduce Running Costs
- Reduce Carbon Output
- Be used with existing pipe work
- Be sympathetic to the building structure
- Fit in the the decor
- Improve user comfort
- Produce sufficient hot water for the occupants
We have replaced the inneficient 18KW gas boiler used for cooking, hot water production and heating with a 16KW high efficiency Panasonic Aquarea air to water heat pump. This produces water at between 30 and 45C compared with the existing system which produced water at between 70 and 80C.
We have replaced the existing 9KW electric water heater with a new 4KW heat pump heater similar to the one we have installed in our office.
We have replaced or improved upon the existing radiators using modern low temperature Jaga Strada DBE models.
Existing System - Running Costs & CO2
Allowing for heating for 34 weeks a year at 86 hours per week with a 70% diversity factor, with the very optimistic efficiency level of 65% for the 18KW boiler gives 56,275 KWhr of gas.
Gas water heating at 100 litres per day for the same period gives 2,343KWhr of gas
Electric water heating for the 18 weeks a year when the boiler is not in use accounts for a further 806KWhr.
Allowing for the following fuel costs taken from a recent utility bill at the property and fuel efficiency taken from the Carbon Trust -
Gas - 2.88p per KWhr and 0.184kg/KWhr for CO2 production
Electricity - 11.4p per KWhr and 0.544kg/KWhr for CO2 production
Total Annual Running Cost - £1,792
Total Annual CO2 production - 11.31 tonnes
New System - Running Costs & CO2
Using the same criteria but using the new heat pump system drops energy usage to 7,778KWhr for the heating.
Water heating is now done solely by heat pump and uses a further 423KWhr for the same quantity of hot water as before.
Using the same fuel cost and CO2 figures as before this gives -
Total Annual Running Cost - £935
Total Annual CO2 production - 4.46 tonnes
As you can see we calculate annual savings of
Fuel Costs - £745 per year
CO2 release - 6.85 tonnes
If you want further details of how we calculated these figures then email us and we will send you the full design brief.
The occupants have been delighted with the results. Operating costs have fallen while the new system is much more comfortable than the previous. In particular the even temperature distribution from the low temperature radiators makes a big difference to user comfort. Like many similar heating systems the occupants have chosen to spend some of the energy savings by heating the entire house to a higher level than before to get year round comfort.
- Improve Energy Efficiency - estimated energy reduction of 51,223KWhr per year
- Reduce Running Costs - estimated annual cost saving of £745 per year
- Reduce Carbon Output - estimated annual CO2 saving of 6.85 tonnes
- Be used with existing pipe work - achieved with no adverse effects
- Be sympathetic to the building structure - No building works were required
- Fit in the the decor - Everything fits in well and the radiators are probably nicer looking than the old ones
- Improve user comfort - exceeds the end users most optimistic expectations
- Produce sufficient hot water for the occupants - More than sufficient and at the correct temperature
In essence the system has achieved everything it set out to do as far as energy efficiency, running costs and CO2 reduction but with the added benefit of dramatically increased user comfort. The reaction time of the system is improved and hot and cold spots have been all but eliminated.