SolarTech Renewable Energy Solutions
Code Level 6 homes at Mendip Place, Chelmsford
Jason Page, assistant architect, Ingleton Wood Architects
At Mendip Place, six houses and four flats for local housing association CHP, the client wanted to use the project as an exemplar, including the way it was procured under a design and build contract.
Because we couldn’t be sure whether all the contractors we went out to tender to were equally aware of the implications of Code Level 6, we decided on a two-stage process. The first was to construct basic Code Level 3 houses, so we got general prices for that, then we asked them in the second stage to provide the “add-ons” — photovoltaic panels, and biomass boilers — to bring the homes up to Level 6.
One of the bidders, McCann Homes, had partnered with SolarTech, which seemed to talk the talk.
We were keen on a “one-stop shop” provider that would have a holistic view about how both technologies would work together.
In effect, SolarTech acted as a kind of M&E consultant, although their figures were always verified by our own in-house M&E expert. They specified a mini-district heating system with energy use monitors to each of the 10 homes. The system was based on two Italian biomass boilers, from D’Alessandro Termomeccanica, each working at 60kV heat capacities.
SolarTech did look at installing just one boiler, but the grant was bigger for installing two small boilers, rather than one big one. It also means that if one fails, the other can kick in to cover it.
PV panels were mounted on the roofs, and are remotely monitored in each home, in anticipation of the feed-in tariffs.
The homes have been occupied since last June. Once briefed on the systems,
the tenants have taken to them and it seems to be working well. The client says the amount of biomass pellets used is more than anticipated, although that might be due to December’s cold snap!
Product news
Pasquill has launched the X Rafter, a pre-fabricated “room in the roof” solution for housebuilders that adds a loft storey to narrow-fronted townhouses. X Rafter is made up of pre-fabricated, pre-insulated, felted and battened structural timber panels, delivered to site, which allows for easy construction of an additional storey. Sequencing involves erecting the two structural gable panels fixed to Posi-Joist floor cassettes. Ceiling supports and roof purlins are then installed before
timber frame dwarf walls are built.
Generally used to working on a bigger scale, Windhager is now introducing a new range of biomass boilers for low energy homes. FireWIN, with an output of 3.8-12kW, is a twist on the traditional hearth and sits in the living room, providing central heating and hot water to the whole house. Alternatively, the utility room-based VarioWIN can output from 1-12kW, but is more suitable for highly insulated homes. The company says that both boilers will qualify for Renewable Heat Incentive grants and can bring a home up to Code Level 4.
Ancon has just launched its TeploTie, an innovative, low thermal conductivity wall tie. The product has been used in the UK’s first residential retrofit built to achieve Code Level 6. Architect John Christophers refurbished his
own 1840s house and preserved the brick exterior by adding internal insulation and using the ties to connect the two leaves, creating a wall that was 16 times more insulated than before. Made from extruded basalt fibres, TeploTie wall ties can be resin-fixed into existing walls. They have a thermal conductivity of 0.7W/m/k.
Tips of the Trade
Saving carbon in housing
| 01 Reduce, re-use, recycle |
Look at reducing the amount of material used. Aim to use reclaimed materials and use them in a way that can
be recovered and re-used at a later date. Consider recycled materials, such as recycled glass or reclaimed bricks.
| 02 Switch to products with lower embodied carbon |
Substitute products that have a high embodied carbon for alternatives that provide the same function. A good example is to use fly ash (or ground granulated blastfurnace slag) in concrete mixtures to replace some of the cement content.
| 03 Examine every aspect of procurement |
There can be huge variation in the carbon footprint of the same product made in two different factories. Select manufacturers that are actively reducing their carbon footprint. Look at how to manage your transport strategy responsibly. For instance, air journeys are 500 times more carbon intensive than shipping per mile.
04 Use natural materials
Natural materials offer more carbon savings than processed ones. Natural softwood timber has lower embodied carbon than wood boards such as medium density fibreboard (MDF), oriented strand board (OSB) and particleboard.
05 Reduce waste
Construction waste can form as much as 15% of the embodied carbon of a house, but best practice methods can halve this figure. Plan ahead, don’t over-order and avoid throwing away new materials — many suppliers offer take-back schemes.
By Craig Jones, senior associate at carbon reduction company Sustain. His new book Embodied Carbon – the Inventory of Carbon and Energy is available through the Building Services Research and Information Association (BSRIA)
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