BRE: Investigation into Longtown Heating Systems

1. BRE: Investigation into Longtown Heating Systems David Butler9 October 2014

2. BRE – Building Research Establishment Ltd • BRE is an independent research based consultancy, free of commercial and government interests and is owned by the BRE Trust. • The BRE Trust is a charity and all of BRE’s profits go back into research and education projects supported by the BRE Trust. • BRE’s scope includes buildings, the environmental, fire, security and safety.

3. BRE investigation into Longtown Heating Systems BRE was commissioned by Riverside to undertake an independent investigation: • Are the new heating systems suitable? • Were the systems and specifications appropriate? • Are the running costs (electricity bills) reasonable or not? • Do the solar PV installations affect the heating systems?

4. Scope of BRE Work • Two BRE specialists: • Heating expert - David Butler • Solar energy expert - Steve Pester • Visited and inspected 5 representative Longtown properties in May 2014. • Provided a detailed report on findings and recommendations to Riverside

5. Choice of heating system • Riverside has provided modern whole house radiator based heating systems. • Mains gas is the cheapest fuel and the standard choice. • Lack of mains gas in Longtown restricted the options. • BRE confirms that electricity is best fuel for Longtown but is more expensive than gas. • Oil, LPG, propane are alternatives but are expensive, have safety and storage issues and potentially large and unpredictable price fluctuations.

6. Choice of heating boiler - ASHPs • Air source heat pumps (ASHPs) can replace conventional boilers. • ASHPs “pump” heat from outside – they provide 2x to 3x the amount of energy consumed to run the machine. • Running cost of an ASHP is similar to a gas boiler.

7. Choice of heating boiler – electric boilers • Some Longtown properties are not suitable for ASHPs • Flooding risk and strength of house walls. • Electric boilers have been used instead.

8. Cost of running heating systems • Whole house central heating provides high comfort levels and convenience. • But, must be controlled sensibly to avoid high heating bills.

9. Heating bills • Most tenants appeared to be on standard electricity tariff or Economy 7 (E7). • Standard tariff is not usually suitable for electric heating. • E7 is designed for storage heaters. • E10 is designed for electric boilers. • BRE has advised Riverside to help tenants choose most suitable tariff.

10. Electricity tariffs • E10 off-peak rate - 5 hours overnight, 3 hours early afternoon and 2 hours in the evening. • May not suit all tenants. • Heating system programmer times should be set to heat house as much as possible during off-peak times. • Hot water timer should heat hot water only during off-peak hours.

11. Electricity tariffs • E10 is not available from all suppliers. • EDF and SSE offer E10. • Check peak and off-peak prices – there may be a difference between suppliers. • Total savings from switching to E10 may be 15 to 20% a year. • Some tenants will need help in switching to most appropriate supplier and tariff and in setting programmers.

12. Solar PV systems

13. Solar PV systems Incoming from main meter • BRE inspected 5. • All were wired & working as expected. • House electricity meter only registers what electricity is consumed from the grid. • A second electricity meter shows how much energy has been generated by the PV. • BRE confirms no interaction is possible with the heating systems. PV generation meter and PV system PV AC isolator

14. Solar PV systems • BRE confirms solar PV systems are working well (4.7 kWh / day in May in one property inspected by BRE). • PV electricity is free to tenant but any surplus power goes to the grid.

15. Making the most of the free PV electricity • Most PV electricity is generated on sunny days when most people use least energy so a lot may be exported to the grid. • A special Power Diverter can be fitted that diverts PV electricity to heat the hot water tank – a form of energy storage. • BRE recommends that Riverside considers installing Power Diverters so that tenants benefit more from the solar PV.

16. Improvements to insulation and windows • The Riverside properties are 60 years old - heating bills can be reduced by improving thermal insulation. • BRE recommends that Riverside continues with investment in improving insulation, e.g. external wall insulation and new windows. • Any defective pipe and loft insulation (BRE and Avoca found some missing or defective insulation) should be rectified.

17. Conclusions • Riverside have provided tenants with a modern whole house central heating system >> higher comfort & convenience. • No mains gas in Longtown means that more expensive electricity has to be used instead of gas. • ASHPs use electricity very efficiency (provide 2x to 3x the energy) but not suitable for all houses. • Electric boilers are usually cheaper to run on E10. • Solar PV provides tenants with some free electricity but the amount may be increased by fitting Power Diverters. • Further investment in insulation and help in setting controls and choosing best tariffs will reduce tenants’ energy costs.