We struggled, at times, to communicate to others what we meant by eco: it took a while for my dad to understand reclaimed, native, or FSC wood and eco-varnish; the plumbers questioned what our washing would turn out like if we used rainwater; and the painters objected to using Osmo and ECOS paint. Early on we met plenty of patronising builders who advised us to ‘forget all that eco-stuff’ and raised eyebrows when they understood we were two women building a house. But with a highly supportive eco-architect (Andrew Yeats of EcoArc) and a knowledgeable project manager willing to engage with eco-ideas we eventually found suppliers and stockists of the things we needed. My partner, friends and family were invaluable in helping us complete the build – with seemingly endless shelving to put up, a woodshed to build, furniture to strip, and gardens paths to lay. Since moving in a local carpenter has agreed to drop off his off-cuts which we use to supplement our homemade newspaper logs and purchased logs for the wood stove, and a neighbour has offered us free seedlings for our garden. Our house has started all sorts of conversations and we have often invited in passers by who have stopped to ask us questions.
At times we have to remind ourselves why we made certain compromises (often due to a lack of money or plot space) and get frustrated that we do not yet generate our own electricity. Now the project is almost complete we have the confidence in our choices to wonder if we couldn’t have been bolder in some of our earlier decisions. Externally the house has a big visual impact on the landscape (ironically a result of the planning permission which stipulated that it replicate the look of the previous house demolished by Network Rail). We have tried to mitigate this impact by covering the lower external walls with red cedar cladding and choosing a dark slate-effect roof (using Ardesia recycled tyre roofing), but we could have been more radical in our design. We now have the confidence to follow our gut instincts and compromise less in our search for environmental solutions. We only hope that our house will inspire others to follow their dreams too.
Project Managers Perspective
Taking on the project management of an eco build was of real interest to our company, we have managed projects of all types and size, the learning curve was much steeper than we thought as sourcing eco materials seemed to be an excuse for increasing the costs, whether it was fsc timber, sheeps wool insulation or recycled aggregate blocks, we had to work hard to get the prices as low as possible and meet delivery schedules. The one aspect that we would do differently would be the selection of and the management of the sub contractors with relation to eco builds and their time schedules as we lost about 9weeks arguing over the floor and roof timbers and this put the rest of the project under pressure. We think that the end result achieved what Maggie and Jenny and Andrew and Eric from Eco Arc wanted and we are proud of the overall achievement.
Architects Perspective: Building Fabric
The client’s aspirations for a low energy house were primarily addressed by designing a relatively compact, well-insulated and air-tight building fabric. The chart below gives an overview of the fabric U-values and air permeability goal for the Gate House compared with the AECB Silver Standard and the 2006 Part L Building Regulations requirements.
||Gate House Design Values
||AECB Silver Standard
||UK Building Regs 2006 Part ADL1
||â‰¤1.4 Wm2K (uninstalled)
||â‰¤1.4 Wm2K (uninstalled)
||â‰¤ 2.0-2.2 Wm2K
||â‰¤ 2.0 Wm2K
||3m3/ m2hr @ 50 Pa
||3m3/ m2hr @ 50 Pa
||10m3/ m2hr @ 50 Pa
The strip foundation footings support a perimeter blockwork cavity wall with 200mm of mineral wool insulation. The ground floor slab was overlaid with 100mm EPS insulation and a screed (with 25mm of perimeter EPS insulation to minimise thermal bridging along the edge of the screed) was laid on top of this to provide the substrate for the timber boarding on the ground floor. The intermediate floor and traditionally cut roof are both timber framed and the roof is insulated with 250mm of sheep’s wool insulation. The solid external doors were insulated and the windows were low-e, argon-filled double glazed units.
Heating and Ventilation Systems
The brief from Maggie and Jenny was to design a house that was cheap to run and simple to maintain and only use technology that they could understand and maintain. These key principles influenced the choice of the heating and ventilation systems.
Mechanical extract ventilation using low-watt fans was chosen over a passive ventilation system primarily to keep the ‘fear factor’ for both builder and client low. Passive ventilation was considered but was dropped as it would have been more difficult to integrate into the blockwork partition walls without visible ducting in several areas.
Maggie and Jenny are both ‘hands-on’ and were happy to use a (12kW Clearview 650) woodburning stove with a back boiler as their main heating source. Approximately 4m2 of evacuated tube solar hot water panels also assist in heating the hot water in a twin-coil cylinder.
Energy and Water Use
Maggie and Jenny are nearing their first full year of living in the Gatehouse and have undertaken some very basic monitoring of their energy use and intend to continue doing so in more detail in the coming year. The following assessment is based on a combination of information provided by Maggie and Jenny and some educated predictions based on the information currently available.
Up until February of this year, the Gatehouse didn’t have a water meter and at the time of writing this article the first water bill hadn’t arrived. The main water saving features in use at the Gatehouse are a rainwater harvester (feeding the toilets and washing machine); low-flush Ifo Cera toilets; low-flow shower heads.
The main fuel source for the Gatehouse is timber. Maggie and Jenny paid £100 for two deliveries of logs plus used left-over timber construction waste (say £50 worth) for a total of £150 worth of wood. At 2p/kWh this would equal 7500 kWh for space (and some water) heating.
The electricity use for the first 9 months of occupation at the Gatehouse was 4000 kWh. This is an average of 444 kWh per month or approximately 5333 kWh per year. This figure translates to 48 kWh/m2yr. This figure is above the average and the client is aware of several issues that have possibly contributed to this: use of electric induction cooker; occasional use of an electric immersion heater; washing machine is cold fill only and requires occasional electric heating. It is also likely that a fair amount of this extra usage has been due to the drying out of the building during its first year of occupation.
User Feedback and Project Summary
Now that we have analysed the predicted energy performance how does the house fare for the clients? The passive solar design combined with the higher levels of insulation have created an internal environment that, according to Maggie and Jenny remains at around 17° C, even without heating in the winter months according to the clients. The use of rooflights ensures high levels of daylighting which has significantly reduced the need for lighting during most times of the day.
The build has been challenging for Maggie and Jenny from the beginning meeting resistance and scoffing from some of the patronising’ builders who advised them to ‘forget all that eco-stuff’ and raised eyebrows when they understood they were two women building a house. Later on during the project, Maggie and Jenny were questioned by the project plumbers on the use of rainwater to wash their clothes and the decorators were equally sceptical of the (Osmo and ECOs) low-voc and water based paints and wood treatments.