Progress...

... has been fairly rapid during the long days of a Scottish summer. Since pouring the floor slabs the timber frame has gone up in a matter of weeks, with work now starting on building up the old dairy's stone walls another 400mm to roof eaves level so our guests will have plenty of headroom upstairs!

Construction design is similar to the house, using an insulated timber frame clad with woodfibre board on the outside for extra insulation and to reduce thermal bridging. This keeps the wind out and, with the help of fancy tapes and membranes on the inside, the heat in. Heating is to be from a ground source heat pump and solar thermal panels, with solar PV offsetting electricity use. Inside we just have underfloor heating on the ground floor which will keep things cosy during the chilly winter months!

Over the next couple of months we should see the roof windows in and the roofs slated, then hopefully, the windows and doors will have have arrive so the cottages can be wind and watertight before the cooler and wetter months...roll on Autumn!

Holiday Cottages Underway

So here we are starting a new and exciting adventure at East Cambusmoon. Three years ago we moved into our house, beautifully designed and immensely energy efficient, see here. We adopted a very low energy approach to the design and the construction detailing which focussed on significant levels of insulation, a high standard of air-tightness, strong passive solar design and a ground source heat pump for the heating and hot water, supported by a small PV array and mechanical heat recovery and ventilation. When we were at the design stage 4 years ago this approach was not widely taken but, even in the short time since we moved in, more people and architects are looking more broadly at how homes and buildings are managed environmentally. We joined the AECB and adopted their Silver Standard for energy use and carbon emissions. In truth the house has far out-performed this standard and even in the last particularly cold winter was warm all day every day at very low cost.

The main difference between the projects are that the house was a new build and the holiday cottages are a conversion of two very tired farm buildings. Notwithstanding our intentions to replicate some of the approaches we took with a brand new building we are very aware that we are renovating an old dairy and byre and will certainly be retaining the architectural features the buildings; the red sandstone which was quarried locally, the arch over the doorway and the window recess with wooden lintel. Here we are creating two adjoining holiday cottages, one of two bedrooms, one of four. As we are in Loch Lomond & Trossachs National Park we hope that some of the year-round visitors to this stunningly scenic area might like to come and stay in the cosy warm luxury of our holiday cottages. As you can see we're just starting the conversion works and we'll do our best to record the journey on this blog.

The building story so far has been one of rapid change. The roofs have fallen in and the rubble cleared out; in the stone building (which will have two bedrooms) the 'hole' for the sliding patio doors has been punched through and the stone stockpiled for reuse; in the larger unit, which was brick built in the 1950s, the walls collapsed so extra blockwork and labour will be required; floor levels were equalised as existing floors sloped. Then we get into the first stage of serious insulation - the floor. So much heat is lost through the floor, don't waste it!

In the past week 200mm of polystyrene and polyeurathane insulation boards have been laid throughout the buildings and on top of this will float 30 tonnes of steel and concrete in the 4 bedroom unit and 15 tonnes of the same in the two bedroom unit. Before the concrete is poured the underfloor heating pipes are installed; this is done by fixing the pipework (large diameter polythene pipe ideal for use with heat pumps) to the steel reinforcement mesh with tie-wraps. This approach works well with ground source heat pumps which have lower operating temperatures than the more frequently used shallow tray form of underfloor heating. The concrete provides the thermal mass necessary to stabilise the temperature and keep those cottages lovely and warm when needed.We're using Anderson Floorwarming for the underfloor heating, hot and cold water systems, installation of the ground source heat pump and solar. We are happily working with the same builder, subcontractors and architect as we did on the house so its nice to see familiar faces back on site.

The ideal low energy house?

What we've set out to do at ECF is to build a house which will use 70% less energy than one built to current building regulations. Its timber frame construction detailing hasn't wavered too far from the 'norm' to present any major problems for a timber frame kit manufacturer, decent building contractor or building control, and the costs of going this 'extra mile' haven't been excessive to the extent that they will be paid back within a decade in terms of reduced energy costs.

In essence, we have built to a standard which is accessable now by most contractors and self builders which is around 5-6 yrs before its time if the UK Government is to fully implement its Code for Sustainable Homes (CSH) strategy, on which this building should come in at around 3-4 on a scale of 1-6. There is clearly some distance to go from this to 'zero carbon', so what represents the 'optimum' for 'Level 6 living', the magical zero carbon level required by 2016 for all new homes?

Well, the same principles apply, namely...

• building orientation to maximise solar gain in winter, spring and autumn whilst avoiding overheating in summer


• high levels of insulation around the entire building envelope


• high levels of airtightness coupled with heat recovery ventilation


• highly insulated and well sealed doors and windows

...but for CSH level 6 the wall insulation would need to be increased to >300mm (from our 200mm), roof insulation to >450mm (from our 350mm) and windows to be triple glazed krypton filled units with insulated frames and glazing spacers (vs. our argon filled double glazed units). This would result in a building which could feasibly rely on the heat given off by its occupants and collected though its windows to keep it at a comfortable temperature without having to introduce a heating system. Construction might rely on internal masonry/concrete walls to store heat and keep a steady internal temperature, with the insulation fixed to the outside of this.

On the face of it quite simple, but a seriously long way from what the UK housebuilding industry is used to. Roll on 2016.....there is a lot of catching up to do and mindsets to be re-programmed.

Good weather = Good Progress

Afterwhat has seemed a long spell of dreich weather, the sun finally came out today and the slaters made significant progress on the roof, now about 75% slated. Inside the joiners completed the poythen vapour membrane work on the 1st floor such that we now have a near airtight house.

As I have mentioned before airtightness is an essential element in low energy housing; it allows the insulation to work properly, prevents draughts and ensures that ventilation can be properly controlled. The old adage 'insulate tight - ventilate right' has to be the watchword for the eco-selfbuilder, and if planned and implemented properly, will go a long way to achieving significant savings in energy even before considering renewable energy systems and high efficiency boilers.