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!

The temperture is rising

I have just downloaded the data from my three recording thermometers and here is the chart. We have been working on insulation, etc, and now have the woodburner going. The indoor temperatures are pretty steady, and have been rising towards the target of 20C (68F), so things are going in the right direction. The boiler hardly comes on for heating now and I will report on the gas usage later on. One for the geeks!

Spring is coming!

Although there was a biting cold wind today, it is starting to feel like Spring. Karen weeded and I hauled manure yesterday following a 5-mile run - we slept well. Today I built two bee hotels for mason bees, who I hope will take up residence and pollinate our apple and pear trees.

And I finished the ductwork for the MVHR - at last!

Cross section of Mason bee nest - you can see the reason for the holes

My Devon Crimson Queen ready to go

Fire

The woodburner is in - it's not Passivhaus, but we wanted the pleasure of a fire

Starting to finish

The heat recovery ventilation ductwork in the loft

The pace has slowed a little, but we are now working on finishing touches.

These will get 370mm ( 15") of insulation on top

Karen adds colour to the kitchen

Glen installing the big whisk

With a globe light

The award-winning Plumen we got from the Cootes looks perfect!

Karen's corner ready for her desk

The globe-trotting Paddy takes time off to build Karen's birthday present. Thanks, Viv!

Karen finishing the painting tonight - she's still at it.

Martiin sealing the countertop to the backsplash. Kitchen is nearly finished.

One more connection to the MVHR to go.

The last of the floors

We have embarked on the last phase of mess and dust - the floors of the laundry/utility room and downstairs loo. Martin started on the slate in the entry hall and will continue this week to finish it off- the new floors at the back will get the same slate.

Simon's crew return tomorrow to install the vapour barrier and new ceiling boards in the back bedrooms to complete the air sealing of the upstairs ceilings. Mr. Sparks is coming to see if he can seal the woodburner flue to the ceiling membrane - I didn't discuss this with him until he had done the job! Things are looking more normal, but there is still a lot to do.

Stapling the mesh to the joists is both awkward and back-breaking

For those who missed it the first time - the sheep's wool insulation, which is pleasure to work with. Thanks to Chris at Back to Earth

Stairs are in!

At last the stairs have arrived.  So far it has taken them four days to install and there is still another two days to finish.  We're delighted with them - lots of attention to detail. 

Hooray - we have stairs for the first time in four months!

Rob's design and Ross's execution - a great combo

Note the little dark inlay of wood on each tread - we think it is walnut

Ian arrived this afternoon with a pile of seasoned oak for our (soon to be purchased) woodburning stove. What a great house rewarming present.

 I spent five hours today cleaning the sitting room - on our return from London last night we were horrified to find a layer of fine sawdust covering everything.  However we will forgive Ross as he's done such a great job on the stairs. Karen

The stair has arrived

At least some of it. It looks great in the space and the walnut ( I think it is) strip on the tread is just right. We still need to resolve the height of the guardrail on the landing, but otherwise it is looking good! Credit to Young and Norgate for their full committment to this project. http://www.youngandnorgate.com/