Case Study – Riverslea – Stokesley

75% CO2 reduction

75% energy reduction

17 Riverslea, Stokesley

The house was completed in 1973, as a detached, brick built, 2-storey property, with 4 bedrooms and considerably modified over the years.

Extensions to all but the front of the house, so the core part of the ground floor of the house is shielded from all but south-east winds. While two of the extensions are not heated, the large sun lounge provides solar gain which on sunny winter days can heat the house.

Recent modifications

Air source heat pump mounted on the side of the house at first floor level.

Air source heat pump (ASHP): gas central heating was replaced with an ASHP.  An ASHP is like a reverse refrigerator, electricity is used to pump / compress / expand a refrigerant fluid within a closed loop, effectively cooling outside and providing heat inside the house.  This replaces the use of gas with electricity, but whereas 1kWh of gas provides 1kWh of heat, using an ASHP 1kWh of electricity can provide up to 3kWhs of heat.

Solar panels: solar panels were installed to provide zero carbon electricity for both household and plug-in hybrid vehicle use.

Battery storage: Battery was installed to allow for local electricity to be available “when the sun don’t shine”.

Radiators: 9 out of 11 radiators were replaced with high efficiency versions, to allow the ASHP to operate most efficiently at 40°C, lower than the 68°C from a gas boiler.

Heating: The ASHP keeps the house at a constant 20°C room temperature.

Historical energy efficiency improvements

The cavity walls were filled with insulation in the 1970’s under a special offer from ICI.  All the windows and external doors were double glazed in the 1980’s.

The sun lounge windows are double glazed, but the roof is not.  The door to the sun lounge is normally closed unless the heat from the sun lounge is needed or entertaining.

The loft is insulated to current regulation and is not used for storage, so the insulation efficiency is not decreased due to compression often caused by the storage of boxes.

Historical usage:

Radiators in the hall and the downstairs bedroom were not used.

The door to the sun lounge was kept close unless entertaining or the heat from the sun lounge is needed.

Renewables: heat

Air Source Heat Pump:- Mitusbishi – Ecodan (16kW)
Supplier/Installer:- Collective Green Energy Yorkshire (GCE), Thirsk
Installed:- 2019
Costs:- Heat pump, installation and commissioning ~ £13,000 – with regular Renewable Heat Incentive payments over 7 years will total £10,000 – so net cost will be £3,000 – without taking into account any changes in energy pu.

Financial support:-. Npower grant £????

Issues to Consider:-

An upfront grant is now available instead of RHI.

The heating system runs at a lower temperature than standard central heating. Therefore, we chose to install oversized radiators to provide the heating rather than dig up concrete floors to put in under-floor heating.

Need a space outside for the heat exchange unit, which is about the size of a wall mounted kitchen cabinet, plus some accompanying pipe work and a small expansion tank. We are pleased with the system which gives a very even heat and provides all our hot water as well.

Renewables:-  Electricity

Solar Photovoltaic & Battery
Year of installation:- 2019 Installer :- Upnorth, Newcastle
Benefits: Generation for use and battery charging, export occurs only when battery is fully charged.
Solar PV Technical details:- ??? W panels giving total peak output of ?.?? kW.
Battery Storage Technical details:- Toyota 5.2kWh giving total peak output of 2kW.

Other Factors

As part of the grant application I had to have a house efficiency assessment 17 Riverslea is rated C. (My understanding is that the assessor will tell you if there is more to do – I could only improve by triple glazing – phenomenally expensive!)

CPC installed in two days they came on time and left on time. The ASHP has coped with the coldest winter days.

Upnorth installed in two days they came on time they left on time – they left me with Givenergy software very useful. The solar panels I have are designed for my roof only. How many and what they produce is just for curiosity.

Initially annual fuel bills reduced from c£1,100 to c£900 (2019/20) – current estimated fuel bill is £1,200 but who knows – and that includes charging my car!

The house temperature is 20°C+ at all times (last week my total fuel bill was 60p – 2kWh) radiators next to an outside wall are switched off at all times

Since installation I have installed an induction hob and a 600w kettle and the only other cooking system I regularly use is microwave.

Personal insights

I approached this as an ordinary householder who was keen to reduce the household carbon emissions significantly, in the end from ~3.1 tonnes to ~700 kg

My approach with my house was to say “Who is out there ‘commercially’ to help me reduce the CO2 my house produces” – that’s environmentalism for you.

Let’s keep the firms in the frame that are LOCAL and recommended :-
E-ON recommended Upnorth to install the solar panel and house battery (from Newcastle).
CGE Yorkshire recommended by Trustpilot to install the heat pump (Thirsk).

You will need to seek out the best companies currently operating as the suppliers have changed since I installed the technologies.

Only charge car when sun shining or battery full.

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