Building type Affordable Housing
Building age 1915-2000
Location Wickhambrook
Cost of work £73,920
District Not selected

Suffolk Housing Society is a Registered Social Landlord owning a mix of 1 and 2 bedroom bungalows sited in Wickhambrook.  The bungalows were due for a heating refurbishment in 2009 and the Society investigated various options for an alternative, greener heating system than the existing electrical storage heaters.

There was no gas infrastructure nearby to supply gas central heating so the Society researched alternative forms of electrical heating systems and decided to retrofit air source heat pumps.

The average SAP rating for the bungalows prior to installing the air source heat pumps was 57.

Sustainability Features

Air Source Heat Pumps – Mitsubishi Ecodan

Air source heat pumps absorb heat from the outside air. This heat can then be used to warm water for radiators, underfloor heating systems, warm air convectors or hot water within the home.

An air source heat pump extracts heat from the outside air in the same way that a fridge extracts heat from its inside. It can extract heat from the air even when the outside temperature is as low as minus 15° C. Heat pumps have some impact on the environment as they need electricity to run, but the heat they extract from the ground, air, or water is constantly being renewed naturally.

Average install cost per unit including hot water system, radiators and all associated pipework = £6k ex VAT

Running costs and carbon savings are currently being monitored over a 12 month period to ascertain the actual performance against the manufacturer’s claims.

 Mitsubishi Ecodan W85 Specification

 Dimensions (mm) Width                                         950

Depth                                                                    330+30

Height                                                                   943

Weight (kg)                                                             77

Airflow (m3/min)                                                      55

Nominal sound level (dBA)                                        48▲

Low noise mode (dBA) @ 7ºC                                     42

Guaranteed operating range (Outdoor)                  -20~+35ºC

Electrical Supply                                                   220-240v, 50Hz

Phase                                                                    Single

Running current (A) [Max]                                        10.3 [23]

Fuse Rating (MCB sizes BS EN 60947-2) (A)                 25

Heating A2/W35 Capacity (kW)                                  8.5

COP                                                                       2.95

Power Input (kW)                                                     2.88

Nominal flow rate (L/min)                                         25.8

Heating A7/W35 Capacity (kW)                                   9.0

COP                                                                        3.85

Power Input (kW)                                                     2.34

Nominal flow rate (L/min)                                         25.8


Design Process

The main objectives of retrofitting air source heat pumps to these bungalows were to:

  • Install a sustainable and eco-friendly heating system, and be pro-active in reducing our CO2 footprint.
  • Reduce our resident’s energy bills by installing a heating system with low running costs.
  • Give resident’s more control over their heating, and offer a system with programmable controls.



We received 50% funding on the renewable element of the installation from the Low Carbon Buildings Phase 2 programme (LCBP2) provided by the Department for Energy and Climate Change.


Green Lifestyle

In order to maximise the benefits from the air source heat pumps the properties also benefit from cavity wall/loft insulation and are fully double glazed.

The residents played a positive role in choosing air source heat pumps as their preferred heating system, and also emphasised the environmental benefits the system would bring.  The retrofit of air source heat pumps has given residents an insight into new environmentally friendly technology, and has promoted awareness in reducing carbon emissions.



The installation of the heat pumps proved very successful and each system was completed within 4 working days.

As the Society is still in the process of monitoring the performance of the air source heat pumps over a 12 month period we will reserve judgement until we have concluded all the facts from this exercise.

What we can say at this stage is that it is vital to take the residents through the installation process step by step to ensure they are comfortable in both operating the system, and understanding how the system works.   Programmable heating systems combined with renewable heating technology are not the simplest concept, and to seek the benefits the user must have a good understanding of their heating system.

Choosing the correct supplier and tariff for your electric is also an important factor to consider.  Air source heat pumps will be operating mainly using ‘on peak’ electricity so dependant on the supplier and tariff, costs can vary considerably.


Suppliers and Professional Services Used

JSH Consultants, Ipswich

Blue Flame Services, Contractors