Case Study: Generation Homes - REEMA homes

Short Description

The project relates to the refurbishment of a neighbourhood of 20 semi-detached 3 bedroom homes which had come to the end of their useful life. The homes are constructed from a non-traditional prefabricated concrete system (PRC) known as REEMA. These non-mortgageable homes were only designed to have a temporary and short life span although despite this many thousands remain in existence in the UK. The walls are constructed from a panellised concrete system with hollow voids possessing no insulation at all and making the homes extremely fuel poor.

Working with residents in the community, two options were considered, demolition and re building of new homes or refurbishment. The existing occupiers opted for the refurbishment option through the consultation process. An option appraisal of the available technical solutions for energy efficient refurbishment was undertaken and compared to the available project budget. As a result of this it was decided to adopt a core package of energy efficiency measures to be applied to all the homes resulting in a 70% reduction in regulated household carbon dioxide emissions per annum.

In addition to the above, three of the homes which were void or empty (and are being used as part of the decanting process while whole house refurbishment works are undertaken) would receive the benefit of a solar package, both PV and thermal, which would result in a 79-85% reduction in annual emissions in use. This higher standard can be referred to as ‘C80’ and is the UK Government benchmark for what all existing homes in the UK will be expected to achieve by 2050 in order to reach the targets of the UK Governments Climate Change Act for an 80% reduction in climate change emissions.

Key Elements

Certification

Full SAP energy modelling software was applied to the baseline case - before work - and again as refurbished to assess the impact of the measures employed. See additional information.

Project Management

The refurbishment work is being carried out and project managed by Radian’s in house contractor (Direct Labour Organisation – DLO) using some specialist sub contractors e.g. solar installations.

Asset Management

Radian’s stock condition survey data and asset management strategy was used to identify the candidate properties. SAP ratings for the homes with formerly un-insulated walls were very poor.

Capacity Building

It is hoped that the low carbon retrofit of this community will have an impact through effective project dissemination as a result of its scale to assist with capacity building. The DLO are learning new skills relating to the technical aspects of C80 retrofit.

Work with Residents

Close liaison with all residents has been in operation from the outset. A dedicated Community Development Officer has been assigned to the project. All residents were questioned with regard to their attitudes towards energy efficiency prior to works commencing and at which time historic running cost data was gathered. One resident has taken a particular interest in the energy efficiency aspects of the project and has benefited from closer liaison to improve his understanding of the environmental retrofit strategy. It is hoped with further support he will emerge as a community champion as the project progresses.

A simple to follow home user manual incorporating energy advice is being produced for residents. A programme of training and advice relating to behaviour change will be targeted at all end users on completion of the refurbishment works to help them save more energy and money. A supply of current cost meters will be rotated between homes.

Funding

The project is being traditionally financed predominantly using Radian’s own funds supplemented by capital grant receipts via LCBP for 50% of solar panels, CERT funding and a contribution from the Local Authority East Hants DC towards the solar renewables.

Partnership Working

Consultant support was sought to undertake the energy modelling only. Energy suppliers will be engaged in relation to CERT funding and assisting residents with PV electrical export. Strong Local Authority partnership exists and is ongoing. Significant interest from policy / strategy and research type establishments is emerging.

Thermal Insulation

An externally rendered insulation system comprising 100mm thickness of phenolic foam is being applied to the three exposed walls. The increased cost of applying a 100mm thickness above 50mm external wall insulation was less than £1,000 (1,100euro). Traditional loft insulation is being increased to 300mm. New double glazed windows are ‘A’ energy rated.

Air Tightness

Air pressure testing both pre and post works to the three void properties has / is being undertaken. Pre test results were in the range of q5.5-6 a result that was better than expected. It is hoped that this level will be significantly improved upon when the post work tests are undertaken. New draught stripped loft hatches have been provided and close attention to detail to seal up all service penetrations through the internal envelope.

Windows and Shading

The marginal cost of installing ‘A’ rated windows above ‘B’ rated was less than 10%.

Ventilation

All homes are fitted with heat recover ventilation. The three void homes have whole house MVHR systems while all others have through wall units in kitchens and bathrooms.

Solar Photovoltaic

A 1.2 kWp array over roof system has been installed to three of the homes. The area of this was limited by the existing hipped roof design.

Electricity Saving Products

Low energy lighting provided throughout internally and externally with PIR and daylight sensors. ‘A’ rated white goods and appliances (fridge / freezer, washing machine and cookers) have been provided to the three void / decant homes. In addition a supply of current cost meters and power down devices will be made available.

Heating and Hot Water

The existing gas heating systems were outdated and are being replaced with new SEDBUK ‘A’ energy efficiency rated gas condensing boilers with improved controls, TRV’s and programmers. Three properties additionally benefit from 3m sq flat plate panel solar thermal collectors to help pre heat domestic hot water.

Cooling

The retained thermal mass of the structure will help reduce the demand for cooling by maintaining a more stable internal temperature and environment.

Solar Thermal

Three properties additionally benefit from 3m sq flat plate panel solar thermal collectors to help pre heat domestic hot water.

Water Saving

The bathrooms of all homes are being replaced and incorporate dual flush toilets and low flow rate showers. Water butts are provided for external use.

Funding

An EcoHomes XB assessment is in the process of being undertaken. Dedicated recycling bins and services for a home office for example plus advice in relation to local public transport are incorporated into the standard specification items and home user guide respectively.

Main Results

The package of measures employed to the dwellings and the consequential effect in carbon dioxide emission reductions can be seen in ‘additional information’ section. For the homes with the solar package it can be seen that the SAP score has been improved from 43 (EPC band E) to 85 (EPC band B). The household regulated emissions have been reduced from 7.5 tonnes to just over 1.6 tonnes which is a significant improvement in the order of 79%.

One of the three void homes to receive the solar package was formerly heated by storage heaters and an electric fire. As the modelled baseline emissions for this home were worse, it has been possible to bring about an 85% reduction in regulated emissions for this property using the same package of measures.

However, the UK Government have set a target of achieving an 80% reduction against total emissions by 2050 i.e. including all household electrical appliances. Against total emissions the Gas baseline case achieves a 67% reduction and the electric baseline a 76% reduction. This means that in order to reach the Governments target the campaign to work with residents to save energy through behaviour change will be essential.

The total cost of the energy efficiency related works including the solar package are around £38,000 (42,000euro) although 50% LCBP funding has been secured against the solar renewables. These refurbishment costs are perhaps high partly as a result of the external wall insulation element of the work, however, it can be seen that this item of has the greatest effect on reducing emissions as a single measure.

It is anticipated that the completed project will be successful in raising awareness of the need for greater retrofit activity in the UK and the challenges this presents. A second phase of the project relating to a further 14 homes is planned for commencement in 2010 and the learning from phase one will be transferred.

Lessons learned

As the project is in progress it is too early to assess the project learning. The project is currently about 35% complete. The three void properties were the first to be refurbished with only the solar panel installation outstanding and scheduled for later in the summer.

What can be concluded is the need for thorough and effective liaison with residents at all stages of the project extending to a campaign of behaviour change in relation to energy consumption. Further, the need for the energy design hierarchy to be followed was key whereby before considering the application of the renewables, the basic energy efficiency measures were improved as far as reasonably practicable first e.g. insulation and air tightness.

Careful detailing of the external wall insulation is required to eliminate potential cold bridging paths for example at lean to roof intersections and around meter boxes.

A full project case study is to be produced and updated as monitoring data is collected.