11

Heat Pumps and the Renewable Heat Incentive (RHI)

By Graham Johnson

27% of UK CO2 emissions come from domestic heating, lighting & appliances

How does a heat pump work??

Heat Pumps

● Defined by where the low grade heat is sourced from

– Ground (8oC to 12oC)... source heat pump

– Air (30oC to -15oC)... source heat pump

– Water (4oC-10oC)... source heat pump

● Concentrates low grade heat (-15oC to 12oC) to provide useful heat for space heating and hot water in your home up to 55oC

● Contrary to popular belief heat pumps are capable of covering entire space/pool heating AND hot water loads annually if required

What is COP?

● Heat pump efficiency is measured using the parameter CoP

● CoP = “Coefficient of Performance

Total energy output (KWh) CoP = ------------------------------------

Electrical input (KWh)

Heat Pump efficiencies

● Electric Heater – COP 1.0!

● Ground Source – Seasonal COP’s 4.5

– Horizontal collector

– Borehole – closed

● Water Source – Seasonal COP’s 5.5

– Horizontal collector eg lake, river, canal

– Borehole – open

● Air Source – Seasonal COP’s 3.5

● Design/installation considerations:– Budget

– Heat loss of building

– Retrofitting can be disruptive

– Emitter requirements

– Available land and access for the ground loops

– Existing utility supplies: 16kW largest on single phase

– Soil type (wet clay = good, dry sand = bad)

– Need large plant room to accommodate pump, buffer tank and pipework

– Can also provide cooling

Ground Source Heat Pumps

Ground source heat pumps – typical excavation

Ground collectors

GSHP - sources of heat from the ground

Boreholes

Large installation: 32kW Viessmann, 200l buffer 500l DHW with LPG backup

Community installation: 16kW Vaillant GSHP

● Design/installation considerations:– Require planning permission

– Require space for outdoor unit and space for plant

– Monobloc or split

– Cheaper and easier to integrate than GSHP

– High temp ASHP can be integrated with existing emitter system

– Low temp ASHP will require special tank for hot water and emitter such as UFH

– Work well in cities/multiple unit scenarios

– Design and sizing KEY (a 16kW ASHP only produces 16KW when it is 7 degrees at -5 it will produce 12kW)

– Noise considerations

Air Source Heat Pumps

8kW Air Source Heat Pump: Domestic application

Daikin Altherma 8kW installation - Lindford

Twin 16kW Air Source Heat Pump: Industrial application

● Underfloor Heating

● Convention Radiators

● Special ‘Low temperature’ radiators

How to get heat into the building?

Example:- Existing 5 bedroom house, existing radiators, double glazed, average insulation, possibility of mains gas, daily family use. Annual energy usage = 36,000kWh

●Oil fuel bill = £2,160 Pa (6p/kWh)

●Gas fuel bill = £1,440 Pa (4p/kWh)

●ASHP fuel bill = £1,340 Pa (3.7p/kWh)

●GSHP fuel bill = £1,170 Pa (3.25p/kWh)

Note: No FIT benefits included only efficiency savings

Running costs comparison

● The concept of the RHI has been around since April 2010 but it was only officially announced in March 2011

● Aim is to encourage people to switch to renewable heat source from fossil fuels

● Many aspects still to be clarified !

● 2 phases:-

– first phase began in Aug 2011

– second phase begins in October 2012

● Phase one: long term tariff support targeted in the non-domestic sectors (industrial, business and public sectors). There is also support for households through the RHPP (Renewable Heat Premium Payment)

● Phase two will see households moved to long-term tariff support.

● See www.energysavingtrust.org.uk

Renewable Heat Incentive

● To qualify for RHI installation will have to be OFGEM accredited. Ofgem will determine whether an installation meets criteria such as acceptable heat use and metering arrangements

● Projects under 45kW will have to use MCS accredited products and MCS accredited installers

● Owner will have obligations:

Maintain equipment

To provide information to Ofgem

To allow inspection

Eligibility Criteria

Domestic Renewable Heat Incentive (RHI)

● RHPP (Renewable Heat Premium Payment) vouchers available - basically a one off payment for 2011/12 until they have sorted out the level of annual RHI.

● Those who take up RHPP will be eligible for RHI tariff from October 2012

● RHI will be backdated for accredited systems installed from 15th July 2009 (but no RHPP available for these systems)

● Eligible technologies and tariff rates - see table

RHPP

Technology Voucher value

Ground Source Heat Pump* £1250

Air Source Heat Pump* £850

Solar Thermal £300

Biomass* £950

* You can only apply if you do not currently use gas as your main heating fuel

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Question Time

● The following technologies are eligible

Ground Source/Water Source Heat Pumps

Solar Thermal

Biomass Boilers

Anaerobic digesters

● Heat will be metered and support calculated from the amount of eligible heat multiplied by the tariff rate.

● The tariffs will payable quarterly over a 20 year period

● Owner of the system will have to apply to Ofgem for the RHI support. Application will be online, by post or over the phone.

Commercial tariff – how it works

Commercial RHI Tariff Rates

Technology SScale STariff Level TaTariff Lifetime

Small Ground Source

<100kW 4.3p 20 yrs

Large Ground Source

100kW 3p 20 yrs

Solar Thermal Less than 200KW 8.5p 20 yrs

Small Biomass Less than 200kW Tier 17.6p

Tier 21.9p

20 yrs

Heat Pumps – The “heat pump cycle”

630kW ASHP Chicken shed installation

• 17,500sqm floor area• 73km of UFH pipe• 280,000 warm chicks

● Chris Huhne has announced that the UK will reduce Carbon emissions by 50% (from 1990 levels) by 2025.

● One technology alone will not provide the solution. A mixture of required but heat solutions are key – look at the following graph.

Introduction