Category Archives: Our House

Home Sweet Home; or There and Back Again

We moved out of our house in September 2014. It was a wrench but had to be done if we were to realise our dream of a comfortable home. Now, fourteen months later, we have moved back, to a completely new environment. The house has been remodelled internally (see Our House Reborn), completely insulated (see If in Doubt, Insulate It), made airtight and given a state of the art ventilation system (see Airtightness and Ventilation) that recovers 93% of the heat from the outgoing air and uses it to heat the incoming air. We have solar panels on the roof, and pipework under our field bringing us hot water and heating via a ground source heat pump (Renewables in a Low Energy House). We have lost a bedroom (knocked two into one) and gained a conservatory. This is going to take some getting used to!

Setting up the blower door test

Setting up the blower door test

Initial impressions are: what a lot of space (the remodelled rooms are roomier!), and isn’t it warm! We shall have to keep adjusting the heating controls until it feels right as we adjust to the climate within the house. So far, the underfloor heating on the ground floor is barely on and the radiators on the first and second floors are cold, but the temperature reads 20.5degrees Celsius. Admittedly, this has been a mild October but it has been very windy at times this week and we have felt nothing of this within the house (unlike in previous years when a windy day meant a very cold house!).

The old saying goes “the proof of the pudding is in the eating”.  In our case, the proof of the airtightness is in the blower door test. In an earlier post in this series, I mentioned that the blower door test performed before any work was done registered 16.9 ach (air changes per hour). In my second post, I said this:
“Although we cannot hope to achieve Passivhaus standard, and will struggle to meet EnerPhit, there is a lot that can be done to improve on 16.9ach. We have our fingers crossed for 3ach, but we shall have to wait and see”. Today, the waiting is over, the second blower door test has been performed, and the result is 2.5ach (an average of 2.2ach at 50Pascals pressure and 2.74ach on depressurisation).

Thermal image showing the "cold" spot on the old end wall

Thermal image showing the “cold” spot on the old end wall

The problem areas found were with the wall which was once the end wall of the original barn and is now an internal wall between the stairwell and the kitchen/living room/bedroom,  and the woodburning stove. The wall was always considered to be an issue, since its solid construction forms a thermal bridge; the test showed that junction points were one degree Celsius colder than adjoining walls, so 19degrees instead of 20degrees, which in a house where the internal temperature is maintained at a comfortable constant 20degrees, this should not prove a problem, condensation-wise. The woodburning stove is another matter. It is a Chesneys Milan 4 Passive, marketed as the only stove suitable for airtight houses. However, the installation instructions, which we only saw when we eventually took delivery of the stove, admit that the stove is not airtight. There is a row of slots behind the door which is inadequately sealed, and through which we had experienced draughts when the wind was blowing hard from the south, but in addition the flue connectors,  although correctly installed were also leaking at the junction with the fire. We removed the fire and sealed up the flue and retested, resulting in a 20% drop in air leakage.  Recalculating the result of the blower door test based upon the blocked up flue gives us a reading of 2ach. This is a phenomenal result! Our house is over 150 years old in places, with a mixture of solid wall and cavity wall construction, and to have reduced the leakiness to only 2 air changes per hour is wonderful! Huge kudos to Green Building Company for getting this result!

I shall be blogging about our first year in our reborn home at three monthly intervals, recording  what it is like living in such an environment. Look out for the next post in February 2016.

For other posts in this series, see:
Our House Reborn
Airtightness and Ventilation
Water, Water Everywhere
Renewables in a Low Energy House
If in Doubt, Insulate It

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If in Doubt, Insulate It

When we first discussed with Bill Butcher of Green Building Company the insulation techniques required for our house, using innovative materials was the last thing on our minds. We had assumed, in our naiveté, that Kingspan was our only option. We were so wrong!

I freely admit I don’t really understand what U-values are; I had never heard of interstitial condensation; I didn’t know that houses were supposed to breathe.

As the design of the renovation took shape, it became clear that our particular combination of extreme environment, solid walls, and rain penetration would require something more radical than just sticking Kingspan on the walls and hoping for the best.

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Innovative materials
Bill researched the available materials and found that the German company Knauf Aquapanel had been supplying an innovative product for passivhaus building, called TecTem. TecTem is made from perlite, an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. When heated to 900degrees Celsius, the water is driven off and the perlite expands, giving a lightweight material with the additional property of being able to absorb and dispel water. It is mold-resistant, fibre-free, eco-friendly, and completely recyclable. It has excellent thermal properties and breathability. It would be ideal for use in the barn part of our house, where the solid walls and lack of damp proof course mean that we have problems with moisture; moreover, the ground floor suffers from rising damp in one corner. Just one snag; TecTem is not currently available in the UK. But Knauf were interested in working with us to provide a solution to our problem and supplied us with the TecTem direct from Germany. In return, we are supplying them with data on the performance of the product. Within our walls, buried behind the insulation as well as attached to some of our beams, are over 50 moisture and temperature sensors. These report wirelessly to an Omnisense monitor that transmits the data gathered to a central database where it can be analysed, coordinated by Tim at the AECB. We are really excited that our project to give us a warm home will help future builders and architects to choose the right materials.

I have already written about the use of Foamglas in preventing thermal bridging on our steel i-beams, and its use as a tanking material along our dampest wall. In addition to TecTem and Foamglas in the barn half of the house, we have another Knauf product, Thermoshell, on the walls of the 1990s extention, that is in the kitchen, living room and master bedroom. Thermoshell consists of two parts. First, on top of the parged stonework, horizontal studs are fixed, comprised of very high density foam called XPS with a layer of OSB chipboard on the outer face. The whole stud is 100mm thick. In between the studs, 100mm batts of Earthwool mineral fibre are fitted. The whole is then covered by a sheet of Intello and a service void is constructed on top using ordinary timber 2×2, with plasterboard and plaster skim completing the wall. Of course, this does have the effect of reducing the dimensions of the room by about 120mm per wall, but once completed the difference in size is not noticeable.

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The really interesting thing about the wall treatments, whether TecTem or Thermoshell, is that the insulation and plasterboard is not just taken down to the floor on each level; it is carried down the whole height of the house in one continuous layer.  The floorboards along the edges of rooms were removed to facilitate this, and where floor joists impinged they were remodelled and ruthlessly taped for airtightness; stud dividing walls were cut away from their junction with the outer walls or removed altogether and rebuilt on top of the continuous insulation. This method ensured that there are no breaks in the insulation and the whole house is warmed as a consequence.

Bill Butcher has blogged about the technical choices for insulating our home on the Green Building Company’s website.

The third innovative material to be used in the house are Vacuum Insulation Panels (VIPs). These panels are attached to the inner embrasure of each window and external door. They were necessary to minimise the depth of insulation around each window where the window could not be enlarged. Our windows were mostly originally cut into a windowless barn, and were made deliberately quite small. The few windows in the newer extension were made to match the small size. We had had new Ecoplus doors and windows installed some years previously and so could not feasibly have the openings enlarged. Moreover, enlarging them would have required bigger lintels and the whole project would have just got completely out of hand! Vacuum panels were the answer.

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VIPs do require special handling. They are made to measure for each flat surface of each opening; they cannot be pierced, and so have to be stuck in place; any other covering material, for example window boards or plasterboard, have to be similarly fixed with adhesive. A far as aftercare is concerned, we do have to be careful not to puncture the panels, so roller blinds fitted into the embrasures are not allowed; but otherwise there is no problem as they are protected by window boards and plasterboard. They are only 10mm thick but have the insulating property of other insulation material that is 100mm thick. More technical information can be found on Bill Butcher’s blog.

Notes

The U-value is the overall heat transfer coefficient that describes how well a building element conducts heat or the rate of transfer of heat (in watts) through one square metre of a structure divided by the difference in temperature across the structure.

Interstitial condensation is a form of structural damping that occurs when warm, moist air penetrates inside a wall, roof or floor structure, reaches the dew point and condenses into liquid water.

For other posts in this series, see:
Our House Reborn
Airtightness and Ventilation
Water, Water Everywhere
Renewables in a Low Energy House

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Renewables in a Low Energy House

Heating
When we first started looking at our house, warts and all, we drew up a wishlist of all the changes we would make if we could. Almost top of the list was getting rid of the LPGas tank and heating the house with something more efficient, lower in energy requirement, and lower in annual cost. I had been keeping records of how much gas we were using and how much we were spending each year. Our LPG tank holds 2,000 litres of propane; we had a contract with the supplier for regular top ups throughout the year, so it was easy to see that we were spending over £3,000 per annum on heating our house. Only a small percentage of the gas was used for cooking, most of it went through our twenty-year-old Potterton gas boiler, and most of the heat that produced then went straight out through the roof and uninsulated walls. We were in effect paying through the nose to heat West Yorkshire!

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We are lucky that we have a field next to our house, albeit a very boggy field. The bogginess, however, is a positive boon if you are planning to lay ground source heat piping, as the ground never freezes and the temperature of the ground four feet below the surface remains pretty constant. A ground source heat pump seemed to be the best bet for us; it is more efficient than air source, and we have the land to lay the pipes. These days the units are compact, only the size of a refrigerator, and fit neatly into the design for our laundry room on the ground floor.

The digging took place in February, not the best time of year in our neck of the woods, as the land is pretty saturated by the winter rains, but Green Source Heat of Glossop found a way, by dint of using large sheets of plywood, to get the mini digger onto the boggiest parts of the garden. Every trench they dug immediately filled with water, and they uncovered several springs whilst digging the two enormous loops that traversed the field from one side to the other. They managed to avoid all of our trees, apples willow and alder, and unearthed a mountain of stone in the process, as well as creating streams to carry the spring water away to the dike beyond our land.

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The Ground Source Heat Pump model we have chosen is a Kensa Compact 6KW. It is manufactured in the UK and comes highly recommended. It is 570mm by 500mm by 900mm high, with a separate buffer tank which is strong enough to take the weight of the pump unit, giving it a small overall footprint. It fits neatly into the corner of the laundry room (which is not within the house envelope), with pipework through the wall into a manifold installed in a cupboard in the guest shower room.

The GSHP output is 40 degrees Celsius (for heating) or 60 degrees Celsius (for hot water); it supplements the solar thermal for hot water, but will supply all of our heating requirements.

Underfloor Heating
The ground floor, excluding the laundry room, was completely excavated, to a depth of 450mm (about 18 inches). A concrete slab 75mm (3 inches) thick was pumped into the ground floor, and a damp proof membrane laid over it. This was topped with 200mm of Xtratherm and a layer of Intello, and the underfloor heating pipes fixed to this. The whole lot was then covered by a screed, bringing the floor up to its original level.

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We were advised that slate or ceramic tiles are best over underfloor heating, as they retain the heat longer than wood. We had intended to have Welsh slate to cover the floor in the kitchen, guest bedroom and hallways on the ground floor, but the cost in recent years has shot up,  making it economically unviable for us, even if it is relatively local. In searching for a reasonable alternative, we have chosen a quartz slate, which is paler than Welsh slate and has a nice rustic feel to it. This slate has probably been transported halfway across Europe, rather than the 120 miles from North Wales, but it still came in at a little over half the cost of Welsh slate; it is sad that a beautiful local product should be so prohibitively expensive.

Radiators
It would have been nice to have had underfloor heating on all floors, but to do that would have meant raising all the floors by several inches and raising the roof as well. This was not feasible, so we have settled for having radiators on the first and second floors. Although each of the radiators is deeper than the usual thin panels, there are fewer of them overall, and they take up less wall space than our old radiators.

The heating requirements for the house have been carefully calculated; with the heat pump we shall be able to heat the whole house to 21 degrees Celsius when the outside temperature is minus 10 degrees Celsius, using only 4.4KW. Since our solar panels output a shade under 4KW, this means, in effect, that our heating costs have dropped from over £3,000 per annum to virtually zero!

Controllers
We have settled for two heating controllers; one will allow us to program the underfloor heating and the hot water, the other will have a mobile thermostat so that we can choose optimum placement. We know that it will take a few months for us to get used to the different methods of heating the house, and this arrangement gives us the best option for getting the necessary adjustment right.

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Woodburning Stove
We loved our Morso Squirrel woodburning stove. It was only small but output a phenomenal amount of heat. Every year we stocked up on seasoned wood and burnt the whole tonne over the winter, supplementing the inadequate LPGas. But such a stove is not compatible with an airtight house, because it takes its air from the room and exhausts it up a chimney, breaking the airtightness seal. It is a common dilemma for people wanting to build a low carbon low energy house in a timber-rich environment, judging by the questions asked on various internet forums. After a lot of research, Green Building Company came up with a solution: a stove which has been specifically designed for Passivhaus application. The Milan 4 Passive stove from Chesneys is built in the UK and has a direct air intake through the wall of the house. It uses a dedicated external air supply and automatically creates a curtain of air to seal the stove chamber when the door is opened for refuelling. Their documentation states that “it is the only stove independently tested that can safely be installed in an airtight environment”. Its output is 4KW the same as the Morso Squirrel, which is the heating requirement for the whole house at minus 10 degrees. Green Building Company say that we will never have to light it! It is a bit of an expensive item to have if its only purpose is as a focal point for the living room, but a fireplace or stove is one of those comforting things that humans seem to gravitate towards, so we don’t regret insisting on having it, even if it does end up as a decorative wood store.

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Solar
Solar, both PV and thermal, was another item at the top of our must-have list of house improvements, but the only southfacing roof is on our garage, and this is shadowed by the house until about 11am on a summer’s day, losing seven hours of sunshine during which modern PV panels would not work efficiently. In the winter, the exposure to sunlight is even worse. Some years ago we had the house surveyed for an Energy Performance Certificate, and it failed miserably because of the lack of insulation and the usage of LPGas as a means of heating. We would not have received the feed in tariff if the energy performance could not be improved.

One morning, I was listening to the news on BBC Radio 4 and heard an item about solar energy in Germany, and the fact that so many southfacing roofs had solar PV that the grid was overloading in the middle of the day, and the government was encouraging more buildings to have east and west facing panels to even the load. A lightbulb went on over my head. OK we couldn’t have the most efficient southfacing panels, but could we have east and west facing panels that would give us similar coverage? After a bit of calculating, and advice from Eco Heat of Hebden Bridge, we decided east-west was our best option; in the summer, we would get heat and electricity from about 4am through to after midday on the eastern side, and from 10am or 11am through to sunset on the western side; in the winter, sunrise is about 8:30am, but because of our elevation (about 53 degrees north) the sun stays low in the sky all day. Even this small amount will give us roughly 4 hours of sun from the east and 4 hours from the west. I intend to monitor this carefully for the first year or two of operation to ensure that my calculations and assumptions were correct.

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After careful measurement of the available roof space, and advice from Andy of Eco Heat, we settled on BenQ high performance photovoltaic panels, which generate 330watts each. With 6 panels on the east-facing roof and 6 on the west-facing we have the best coverage possible in our situation. We also discussed at length having the panels inset into the roof and this was the initial plan. The panels would lie flush with the tiles and look very neat. However, we have Velux windows in our roof, and even having wide but shallow Veluxes still did not allow enough room for the inline panels and the necessary flashing around them. We therefore had the panels installed on top of the roof tiles. The solar PV panels have been generating electricity since the middle of August. Initially, approximately 12KWh per day (figure based on the first week of operation during the last week of August 2015 when there was a lot of cloud and significant amounts of rain), although as the autumn progressed this dropped to 10KWh  per day on average. We shall be monitoring the performance closely.

The solar thermal panels are also installed on top of the tiles, two on the east and two on the west. The panels selected are Orkli Solar Keymark. The deemed input to the hot water cylinder is 2,328KWh per annum.

Hot Water
The hot water cylinder is heated by the solar thermal panels and the ground source heat pump, with an electric immersion heater as belt-and-braces backup.

Belts and braces
As you can see, we have gone a little overboard in our belt and braces approach to heating and hot water. Our caution is borne of long experience living here. We tend to suffer from breaks in electricity supply; most are brief, short glitches in power that cause everything to turn off and then back on again. But occasionally, there is a longer outage. Earlier this year, a van hit a wooden pylon a mile away and left us with no power for 5 or 6 hours. A few years ago, on New Years Eve, heavy snowfall brought down a power line a few hundred metres from us, and we were without power for 24 hours, during one of the coldest spells we have encountered. We wanted to minimise the very real disruption such outages cause, so we have tried to double up on most things. In the event of a lengthy power outage, we have decided that the pragmatic approach is to have a small standby diesel generator which will at least keep us in hot water and refrigeration. This may not seem very green of us, and normally I would agree,  but the alternative was to have a back boiler on the woodburning stove with very long flow and return pipes to the hot water cyclinder. No such model of stove exists for an airtight house, and the pipework would have been very difficult to retrofit into the fabric. We have therefore gone with the pragmatic solution. We shall probably only have to use it once every couple of years, if that.

See other posts in this series:

Our House Reborn

Airtightness and Ventilation 

Water, Water Everywhere

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Water, Water Everywhere

We are very fortunate that, outside our back door, we have a field roughly an acre in size. Unfortunately, it consists of half bog and half stone. The stone makes cultivation difficult (some pieces weigh half a ton and would be ideal for dry stone walling), and the bog is wet all year round, except in the winter when it resembles a shallow lake! The water-logged nature of the land has meant that the ground source heat pump pipes will maintain a more even temperature even though they were more difficult to lay initially (the trenches filled with water as soon as they were dug!).

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In the past we have planted Alder and Willow in an attempt to soak up some of the water, and have managed to reclaim a corner of the field where it is slightly less damp than elsewhere, but have never really made much impression on the water levels. Every winter the water table rises higher and higher until it engulfs the lower end of the chickens’ compound and the poor hens are paddling.

Needless to say we find a lot of frogs and toads on our land, local mallards occasionally visit, even a few moorhens have investigated the field. We wanted to encourage a more diverse wildlife population, perhaps have resident ducks, dragonflies and other insects.

When the trenches were being dug for the ground source heat pump, we asked if the workmen could dig us a pond, with a small island for security (should any ducks decide to make it their home),  and a stream to carry water from our many small springs to the pond and another stream to take excess water away into the watercourse beyond our land. Our field had always drained into the watercourse, we just made the operation more efficient. The pond looked barren and bare to begin with, but certainly did its job; within a week or two of the pond being dug, we were able to walk across the lower part of our land, something we have been unable to do in nearly 18 years!

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In only a few weeks, we have been able to start planting up the margins of the pond with Iris pseudacorus, purple loosestrife (Lythrum salicaria), Marsh Marigold (Caltha palustris), Duck Potato (Sagittaria latifolia), Red Water Dock (Rumex sanguinea), Ragged Robin (Lychnis flos cuculi), and Lesser Spearwort (Ranunculus flammula). In the pond itself we planted Hottonia palustris and Water Soldier as oxygenating plants. I also researched the types of reed required to help purify the water, as some of the water flowing into the pond would be liquid runoff from the package sewerage plant. Eventually, we bought 150 Norfolk Reed (Phragmites australis)   plants and 50 Common Reedmace (Typha latifolia) to plant along the streams and around the pond. These have been happily growing all summer and have burgeoned into a mass of vegetation.

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Within weeks of the digging having finished, the grasses and sedges started to recolonise the bog, and the summer has given the growth a huge boost. Now, only six months after the pond was dug, you would not know that the land had been disturbed at all. Mallards have been spending increasing amounts of time paddling around the island or snoozing on the bank of the pond. The water’s surface has been alive with water boatmen and these have proved a source of food all summer long for the many swallow families that nest in nearby outbuildings. I have spotted rooks from the local rookeries drinking and bathing in the shallows at the edge, as well as blackbirds and wagtails. Even a heron visited us, stood on the pond bank for half an hour, then waded around the island and ate something (we couldn’t see what!)

It will be interesting to observe the visitors to the pond through the changing seasons, particularly over the coming winter.

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Airtightness and Ventilation

Before I met Bill Butcher of The Green Building Company I had never heard of Air Changes per Hour (ach), the accepted measurement of how draughty a house is. Government regulations for new buildings say that new houses have to have 10ach or less (actually expressed as 10 m-3.h-1.m-2@50Pa (metres cubed, per hour, per metre squared of external building envelope area); Passivhaus standard is less than 1ach; to qualify for EnerPhit a house has to have 1.5ach or better. Before work began, but after our furniture had been moved out, Bill had a local company test our house, using a Blower Door Test; the result was 16.9ach. This despite having well-fitting triple glazed windows and doors. I hate to think what the result would have been if we had had it tested when we moved in 17 years ago, probably equal to living outdoors! Although we cannot hope to achieve Passivhaus standard, and will struggle to meet EnerPhit, there is a lot that can be done to improve on 16.9ach. We have our fingers crossed for 3ach, but we shall have to wait and see.

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Taping around the roof trusses

Firstly the roof needed to be removed, and the felting replaced with Solitex, the standard under-slate covering. That made it weatherproof, but not windtight. Under the Solitex came three thicknesses of Earthwool mineral wool laid in a vertical-horizontal-vertical sandwich. The wool was held in place by sheets of Intello, a vapour open plastic membrane taped around all trusses and joists with Proclima tape; and on top of the Intello, a 100mm block of Xtratherm, similar to Kingspan. The new triple-glazed Velux windows were installed and packed around with extra mineral wool, and plasterboard and plaster skim covered the Xtratherm. All of this material replaced a layer of rotting 1990s felting, a single layer of mineral wool and a layer of plasterboard. The Proclima tape and the Intello are standard products used in building Passivhaus buildings, and it was impressive to see the attention to detail used in applying the tape; absolutely every nook and cranny was taped up, every joist, every window reveal, everywhere that any air could have got in.

Taping around the windows

Taping around the windows

The edging floorboards were also taken up allowing the insulation that would eventually be applied to the walls to be carried the full height of the house, with no gaps between floors. All floor joists were also taped.

Before insulation could be installed, the external walls had to be parged to ensure wind tightness. This was done with a mixture of sand and cement, and covered the internal walls and around the window reveals.

Bill has already discussed the decisions surrounding the internal wall insulation (IWI) materials in his blog. I will cover it in a later episode; suffice it to say that we are enthusiastic about the conclusions reached!

 

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Taping around the floor joists

Ventilation
All the wind tightness measures ensure that as little air as possible blows in, so how do we breathe once the windows and doors are closed? The answer is Mechanical Ventilation and Heat Recovery (MVHR). This is standard kit in Passivhaus construction, and designed into the fabric from day one, so that the effect is seamless. In a retrofit such as ours, careful consideration had to be given to placing the pipes so that every room had the appropriate outlet – extraction from bathrooms and kitchen, but blowing into every other room. The ceilings were only just deep enough in some places to fit the 150mm diameter pipes, and bends in the pipes have had to be accommodated in boxing. Moreover, the pipes running down from the top floor (where the MVHR unit is housed) to the ground floor are contained in a vertical box, reducing the sizes of both the top floor shower room and the middle floor bathroom. We have lost the vaulted ceilings on the top floor as the apex was needed for the MVHR pipes to take them across to the top floor bedroom, but this means that we can have inset ceiling lights, which helps enormously with the head height in the top floor rooms. You win some, you lose some. On the whole  though, we are very pleased with the way everything has been laid out.

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The Paul Novus 300 MVHR unit and pipework

The MVHR unit draws fresh air into the house and passes it through a heat exchanger, which extracts the heat from the outgoing stale air and uses it to heat the incoming air. The unit we have installed, Paul Novus 300, has an efficiency rating of 93%, meaning that 93% of the heat from the outgoing air is recovered when operating at 200 cubic metres per hour. This is a similar unit to the one installed in the Denby Dale Passivhaus (certified at 0.4ach) and at the Golcar Passivhaus (0.26ach).

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MVHR pipes in the Plant Room

The Plant Room
The Plant Room is a narrow windowless room running the width of the house. It used to be our attic room, housing hot water cylinder, cold water tanks, and as much junk as we could squeeze into it. Now it is high-tech heaven. It has the MVHR unit in one corner with the inlet/outlet pipes through the eastern wall, the pumps and inverters for the solar thermal panels and the photovoltaic panels (more about renewables in a later post), and an enormous highly insulated 300 litre heatstore/hot water cylinder. There will be very little room for our junk storage!
The hot water cylinder is heated by the solar thermal panels and the ground source heat pump, with an electric immersion heater as belt-and-braces backup. The solar thermal pumps and the MVHR unit also require electricity (as does the ground source heat pump on the ground floor), so we have 12 BenQ 330watt photovoltaic panels mounted six on the eastern side of the roof and six on the western. We shall be monitoring the performance of these,  since this is not the usual placement for solar PV, preference being given to south facing roofs.

See also:
Our House Reborn

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Our House Reborn

We have lived in our present house for seventeen years, and wanted to continue living in it, but there is no denying it is a bit of a money pit! In those seventeen years we have spent countless weekends and evenings mending water pipes, mopping up leaks, just firefighting problems with acid spring water in standard copper pipes and copper hot water cylinders. We have spent a lot of money replacing our hot water cylinder at regular intervals because of the acid water, decorating rooms only to see the damp seep through the walls and ruin the paintwork, employing useless builders to try to rectify problems with damp only to find the situation is worse after they have finished. The draughts whipping through the house on windy days (that is most days up here on our hill) made the place cold and uninviting. On top of all that are the day to day bills for running a house with no mains sewerage and no mains gas; in a word, astronomical.

When the window frames rotted I researched replacements. I didn’t like Upvc,  nor the standard metal units generally available, I wanted something made from a sustainable material that would do the job properly. That is when I found The Green Building Store. They are local, they manufactured Eco-plus triple glazed windows and doors, and they were committed to low-energy, eco-friendly building, especially Passivhaus. We had most of our windows replaced by them and immediately noticed how much warmer the house was. They also put right some of the problems caused by previous builders, and there is no doubt that they made a huge difference, but the house still ate money. Time for something radical.

We drew up a plan for what we wanted: use our acre of boggy land and our rooftop to provide us with warmth and energy, replacing the expensive LPGas; insulate the house and stop up the draughts; replace our cesspit, which has to be emptied every two months (at great and increasing expense) with a package sewage plant; in a word, make the house live-in-able in a sustainable way. Since insulating would require the removal of all the internal plaster, we decided to have some of the rooms remodelled to make them more useful for us. The project had taken on a life of its own!

The Builders
Although Green Building Company are primarily Passivhaus builders, they saw our house as an opportunity to demonstrate that a typical stone-built house in an extreme environment could be retrofitted to provide low-energy comfort. The fact that we have both solid wall and cavity wall construction in one property made it ideal for demonstrating the differing techniques required to make this possible. After all, most of the 24million houses in this country were built using one or other of these methods, and although the remodelling meant that our retrofit has been radical, the basic principles apply; with properly trained and motivated builders and owners prepared to put up with a bit of mess for a week or two, it is possible to bring the UK housing stock into the twenty-first century and reduce energy consumption in heating our homes.

The old beams

One of the old wooden beams

Remodelling
Ours is a house of two halves: the old barn with thick walls of solid construction, no damp proof course, and roof trusses that impinged on the top floor design, making some of the rooms awkward; and a modern construction extension with dpc and cavity walls, housing one room on each floor.
One of the bedrooms in the barn, a narrow room which we used as an office, had to be accessed through a narrow door and up a separate set of stairs. Off this room was a small attic room, accessible only by crawling on hands and knees through a low doorway. On the ground floor was an annexe, also accessible up a separate flight of stairs. The annexe consisted of two narrow bedrooms, a tiny shower room, half of which was located within the adjoining garage, and a corridor. This annexe was our guest room, but neither of the rooms was really large enough to accommodate a double bed. The annexe always felt very claustrophobic to me.

Trusses in the 1990s extension roof

Trusses and rafters in the 1990s extension roof

We drew up plans, with Green Building Company, to restructure the roof, using steel beams instead of the massive wooden ones. These i-beams would be hidden under the floor, and the weight of the roof taken by upright struts and plywood. The structural engineers assured us that this would work!

The annexe would go, and a new guest suite would take its place, accessed from a door opposite the kitchen. The archway through the original wall taking the shower room through into the garage would be blocked up as the wall formed the edge of the thermal envelope. The internal walls would be demolished and what had been the stairs up to the annexe and the corridor within it would become the en-suite shower room for a large guest bedroom.

New steel beams in place

New steel beams in place

On the middle floor,  there was also some remodelling to be done. With the removal of the LPGas boiler, the cupboard under the stairs (leading to the office) that had housed the boiler would be redundant, and the removal of the stairs to the office meant that the space could be incorporated into a room (next to the boiler cupboard). This room had originally been a dining room, when the kitchen had been on the middle floor. Later, I had annexed it as my sewing room, although it had largely been used as a dumping ground. The old kitchen on the middle floor was to be ripped out and turned into a bathroom, but with all the kitchen cupboards removed it was shown to be a spacious room, rather large for a bathroom. We decided to take some of that space, equivalent to the width of the gas boiler cupboard, and add it onto the sewing room enlarging that room by about a quarter. In effect, we are turning a five bedroom house, where three of the bedrooms were too small to be practical, into a four bedroom house where the rooms provide flexibility of use and better overall accommodation.

Building Works Begin
In September  2014, we moved into rented accommodation. We both felt a wrench at leaving our home, but kept telling ourselves it would be lovely when it was finished! We had debated whether to store everything and have a caravan on site, but eventually decided that we didn’t fancy spending a Yorkshire winter in a caravan so we would rent. We found a very nice cottage a mere five minutes drive from home, and managed to squeeze most of our stuff into it, although we do have to edge around the furniture it is so crowded!

Closeup of a block of Foamglas

Closeup of a block of Foamglas

The builders moved in with a couple of cabins, one for them and one for us, and work commenced. A daily skip delivery removed masses of material. We were pleased to hear that the skip company sorted the waste and recycled as much as possible, as we hated to think so much material was going into landfill. Some things we saved for reuse – the bathroom suite would be reinstated, for instance – other things, like the nearly new stainless steel hot water cylinder, would go on Ebay. The house started to change before our eyes, with walls disappearing daily, the roof tiles being removed and the plaster ceilings coming down and revealing the different roof structure between the old barn and the 1990s extension.

Foamglas in position

Foamglas in position

Because we have used steel beams in the barn to support the roof, there is a danger of thermal bridging. This we have overcome by using FOAMGLAS® Insulation, manufactured from specially graded recycled glass (≥ 60%) and readily available natural raw materials such as sand, dolomite and lime. The insulation is totally inorganic, contains no ozone depleting propellants, flame resistant additives or binders, nor does it contain VOC or other volatile substances. It is very light but very strong. The ends of each beam set into the walls were surrounded by Foamglas bricks to stop the bridging. We have also used Foamglas as a tanking material on the ground floor (more about that later).

To be continued . . .

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