The blog

Roger Hunt is an award winning writer and blogger specialising in sustainability, old houses, housebuilding and traditional and modern building materials. He is the co-author of Old House Handbook and the companion volume Old House Eco Handbook.

Testing zero carbon

Greenwatt Way, in Slough, Berkshire, is more than a zero carbon Code for Sustainable Homes Level 6 development. It’s a live testbed for, amongst other things, five different types of energy generation. This means it has an energy centre on a scale very different from what I had expected of a ten home scheme made up of two and three bedroom houses and one bedroom flats.

For a start there’s the 8,000 litre thermal store weighing in at 11 tonnes when empty, 19 when full. This is connected to a low temperature district heating system – designed to reduce heat losses and maximise heat source performance – which pipes hot water through heat exchangers in each of the homes to feed the hot water supply. The bathroom towel rails and single radiator which, due to the high levels of insulation within the homes, are all that’s required for space heating are fed directly by the district heating system.

Energy generation currently consists of air and ground-source heat pumps, a biomass boiler, solar thermal panels and solar photovoltaic tiles – one bay within the energy centre sits empty awaiting a fuel cell. Each of these technologies has been sized to meet the full heating requirements of the site and the heat pumps and biomass boiler will be run independently to demonstrate their ability to meet the energy needs of the homes.

Behind Greenwatt Way is SSE (Scottish and Southern Energy) which is investing over £3.5m. The scheme was designed by PRP Architects, built by Bramall Construction and engineered by AECOM. The homes are being rented out to SSE and Slough Borough staff, along with local residents and, for the next two years, will be monitored to improve understanding of energy usage and requirements and the individual occupant’s interaction with the homes. The findings will contribute to studies which SSE is carrying out in collaboration with the University of Reading, NHBC and BRE.

As PRP Architects explained to me, Greenwatt Way is primarily designed as a place where people will want to live. The aim has been to replicate a larger, ‘healthy’ community where good neighbourhood interaction helps encourage a more sustainable lifestyle. For this reason there are community as well as private spaces and the residents have to walk past one another across the development to reach the communal bins, bike store and car parking.

See cutaway of house here

Key features:

  • To reflect the different construction methods used across the UK, four of the homes are built from timber frame and the remainder in masonry block.
  • The homes were deliberately oriented to have east and west facing façades as this is the most challenging orientation to deal with both in terms of passive solar design and in maximising south facing roof areas.
  • A high efficiency of heat recovery was necessary on the ventilation system, with summer bypass and a natural ventilation strategy to mitigate overheating in summer.
  • A north facing rooflight above the stairs in the homes allows natural daylight penetration and, in summer, provides an opening to draw warm air out of the house.
  • Low water use fittings are used and the homes include a grey water system for recycling bath and shower water to flush toilets and recover waste heat. A centralised rainwater harvesting system collects rainwater which is stored and used to flush toilets and provide water for irrigation and car washing.
  • The roofs of the homes are covered with solar PV tiles (63 kWp in total) which provide enough renewable electricity to achieve net zero carbon emissions in each of the homes irrespective of heat source.
  • The homes include low energy lighting, the latest energy efficient kitchen appliances, VPhase voltage optimisation and smart meters which SSE will use to monitor the homes’ energy and water usage.
  • Outside, the houses have their own private patio as well as a communal bike shed and garden with space to grow vegetables. Charging points have been installed for electric vehicles.

Image credits: PRP Architects

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SPAB Working Party

For the last 25 years conservation experts and volunteer heritage enthusiasts have come together to join the annual Working Party run by the Society for the Protection of Ancient Buildings (SPAB). I went along to join them and created a video about the Working Party at Sullington Manor Farm near Storrington, West Sussex. They were working…

Listed building allure

Listed building allure

Every year, many of the estimated 450,000 listed buildings in the UK change hands on the property market. In England and Wales these properties are designated Grade I, Grade II* or Grade II having being deemed to be of historical, cultural or architectural interest. All buildings built before 1700

Environmental Pocketbook

Environmental Pocketbook

If you’re going to invest in just one book on sustainable, low carbon building I’d strongly suggest that you make it The Environmental Design Pocketbook. Now in its second edition, this useful volume by Sofie Pelsmakers should be essential reading for architects, designers, developers, planners, students, clients and anyone else involved in the construction and operation of buildings….

Fire in old buildings

Fire in old buildings

The devastating fire at the Grade I listed, 18th century National Trust mansion at Clandon Park, Surrey, once again highlights the need to do everything we can to protect old buildings. Whatever the size of the building, there are simple measures that can be taken to reduce the risk of fire, ensure early warning of a…

Adapting old buildings

Adapting old buildings

The need for fresh air and light in buildings is something I’m often talking and writing about because it’s central to creating a good home, but the theme is nothing new. I was reminded of this when I recently visited the King Edward VII Estate, near Midhurst, West Sussex. Here, the former sanatorium is being…

Building lime knowledge

Building lime knowledge

Lime, in the form of mortars, renders, plasters and paints, is a key component of old buildings and essential to their repair – or at least it should be. Today lime-based materials are also emerging into the mainstream and being used within low carbon construction systems, employed in everything from homes to superstores. All this…

Drain problems

Drain problems

A blocked drain is not a pleasant thing to wake up to. What’s worse is the realisation that it’s something that can generally be avoided by doing what I’m always talking about: maintenance. The drainage system is easily forgotten because much of it is hidden away underground but, as with any element of a building, it…

Building remembrance

Building remembrance

Visiting Blood Swept Lands and Seas of Red, the poppy installation at the Tower of London, reminded me that the built environment frequently plays an important part in both remembrance and memory. Each of the 888,246 ceramic poppies that flood the moat of the Tower depicts a death in the British forces in the First…

Materials testing

Materials testing

New techniques and materials aimed at producing low carbon solutions mean this is an exciting time to be involved with new build and retrofit. There are dangers though, in the rush to innovate there may be failures along the way so it’s vital that there’s scrupulously testing and monitoring at all stages. This is why…

Hidden London

Hidden London

Impending development often means there is a chance to step back in time because archaeological investigation may be undertaken as part of the work. This is especially true in London where layers of history have been laid down by successive generations as the city has evolved. Visiting Barratt London’s Landmark Place site close to the…

SPAB Working Party

For the last 25 years conservation experts and volunteer heritage enthusiasts have come together to join the annual Working Party run by the Society for the Protection of Ancient Buildings (SPAB). I went along to join them and created a video about the Working Party at Sullington Manor Farm near Storrington, West Sussex. They were working…

Listed building allure

Listed building allure

Every year, many of the estimated 450,000 listed buildings in the UK change hands on the property market. In England and Wales these properties are designated Grade I, Grade II* or Grade II having being deemed to be of historical, cultural or architectural interest. All buildings built before 1700 Tweet

Environmental Pocketbook

Environmental Pocketbook

If you’re going to invest in just one book on sustainable, low carbon building I’d strongly suggest that you make it The Environmental Design Pocketbook. Now in its second edition, this useful volume by Sofie Pelsmakers should be essential reading for architects, designers, developers, planners, students, clients and anyone else involved in the construction and operation of buildings….

Fire in old buildings

Fire in old buildings

The devastating fire at the Grade I listed, 18th century National Trust mansion at Clandon Park, Surrey, once again highlights the need to do everything we can to protect old buildings. Whatever the size of the building, there are simple measures that can be taken to reduce the risk of fire, ensure early warning of a…

Adapting old buildings

Adapting old buildings

The need for fresh air and light in buildings is something I’m often talking and writing about because it’s central to creating a good home, but the theme is nothing new. I was reminded of this when I recently visited the King Edward VII Estate, near Midhurst, West Sussex. Here, the former sanatorium is being…

Building lime knowledge

Building lime knowledge

Lime, in the form of mortars, renders, plasters and paints, is a key component of old buildings and essential to their repair – or at least it should be. Today lime-based materials are also emerging into the mainstream and being used within low carbon construction systems, employed in everything from homes to superstores. All this…

Drain problems

Drain problems

A blocked drain is not a pleasant thing to wake up to. What’s worse is the realisation that it’s something that can generally be avoided by doing what I’m always talking about: maintenance. The drainage system is easily forgotten because much of it is hidden away underground but, as with any element of a building, it…

Building remembrance

Building remembrance

Visiting Blood Swept Lands and Seas of Red, the poppy installation at the Tower of London, reminded me that the built environment frequently plays an important part in both remembrance and memory. Each of the 888,246 ceramic poppies that flood the moat of the Tower depicts a death in the British forces in the First…

Renovation tale – Part 1

Renovation tale – Part 1

This is the tale of my first major renovation project some years ago… On the table is the surveyor’s report; yellow Post-it notes stick from its pages in such profusion that they no longer have any relevance. Phrases like “needs attention”, “must be thoroughly overhauled” and “a fair amount of dampness” are highlighted by marker… Continue Reading