Now we have lights

We finally got our electrician back to install the remaining outdoor lights and sign of his installation for building regs. We should be legal soon. Thanks to Tony Taylor for doing some high-tech lighting models for the sunroom. It has all worked out brilliantly (so to speak).

The spotlights in the sunroom

Spring is coming, I'm sure

But it still feels like winter - we were working this weeking with a high of 4C (39F) and a sharp east wind. But I got my early birthday present installed - stainless steel rigging to train two hornbeams on the front door portico. Karen and I both worked on clearing the remaining asphalt from the planting beds - we just need some more topsoil and the trees can go in. In fact we are lucky that it's still winter - our planting season has been extended. Karen put the broad beans in anyway.

It has been relentless grey, but I went out to take a photo of the south side, and the sun obligingly came out.

Winter update

 I know some people still visit this blog, but we have been enjoying the house and getting out and about rather than doing jobs. But things are still happening. The sunroom glazing was installed in December by James Brewer and his mate- it really works! I love sitting out there when the sun is shining and basking.

We are also getting energy results that better reflect the design intent. One day I will update the Passivhaus Planning Package to see what that predicts. Meanwhile, we our annual gas usage is 57 kWh/m2a, compared with 171.5 kWh/m2a before we started, a reduction of 67%. (That high bar on the left was December 2011, when we had done most of the work, but not finished the insulation or airtightness. There is more air sealing to do!)

My own goal was to reduce by 80% - we could do better if we had a solar hot water collector installed. That may come when the Renewable Heating tariff is introduced and we actually shell out for the collector. The red line represents 120kWh/m2a, another Passivhaus target. We are doing well in that regard.

Airtightness update 1

Section showing cold air in the cavity

We have an internal cavity wall, due the house having two bedrooms added at the back. I failed to have it filled when we were bashing the house around, but it showed up as the source of a major air leak in our airtightness test. So today we had the cavity filled with polystyrene beads. The sections shows how cold air can infiltrate the house - even without air movement there could be convected heat loss, so we hope this will make a significant difference.(the cavity does connect top to bottom, but this section is through a door)

The boys wer pretty tidy

PVs are working

We installed the photovoltaic panels about a month ago, so we have the first results. Our electricity from the grid went down from 278 units to 98, and we generated 179 units. Therefore we generated more than we used from the grid, and our electric bill for the month will be about -£25. This was not a main element of the design, but it made sense for us to take advantage of the feed-in tariff. We will be more focussed on our electricity use as well. Photos of the PV installation tomorrow. The gas usage was high in January because we hadn't finished insulating and commissioning the MVHR - and it was cold! Next winter should be much better; we have used about 42% less gas for the first six months than we did before, but intend to get closer to 80% less when we sort out the airtightness.

No, we're not finished

We conducted the first airtightness test last Monday, and the results were a little disappointing. At least I know where to apply effort to improve things. This is one criteria that will probably ensure that we can't get Passivhaus EnerPHit certification. Have to see what the remedial work gives us. For you cognocenti (and the others), the original house was a typical 1950's job, with and airtightness around 16 ach (air changes per hour) or more. Current regulations for newbuild is 10m3/m2, close to 10ach. We achieved 4.5 ach, but the  target is 1 ach. So lots to do. The internal cavity wall is one culprit that will be hard to correct.

Door fan in place, with monitoring equipment connected

MVHR pipes into leaky duct - needs proper sealing at the first floor ceiling.

MVHR filters bagged and taped to avoid air leaking out or in

MVHR is commissioned

We finally have a working Mechanica Ventilation with Heat Recovery system working! Graeme Bonds from Titon dropped by this evening and we balanced the system.

The anemometer in place

It reads 8 litres per second- a little more that we need in the WC.

There are two small fans, one supply and one extract that run continuously during the heating system. The incoming cold air passes through the heat exchanger which transfers the heat from the  moist outgoing air to it, returning the heat to the house.

When a house is well insulated, the proportion of heat lost through ventilation goes right up. The illustration below shows that in a low energy house with normal ventilation, the ventilation heat loss is equal to the fabric heat loss (through walls, windows, roof and floor). In a Passivhaus, the ventilation is controlled and heat is recovered. We won't know until we have been through a full heating season, but we know we started out on the far left of this chart, and are aiming for the Passivhaus retrofit standard, which is nearly as good as the new-build Passivhaus.

The humidity is lowered, increasing comfort in the winter. In warmer weather, a thermostat shuts down the supply air and runs the extract only - the windows are open for fresh air!