This posting is mainly a lot of photos showing some of the detailing around the windows. 

The key thing to note is that because we have replace the windows, the thicker sash boxes that are needed to accommodate the thicker windows meant that the boxes stuck out further than the wall.  This means in effect there are no reveals.  This picture shows the box sticking into the room past the brickwork.

In order to eliminate any cold bridging the insulation was continues over the box frame.  This was achieved by cutting a section on the rear out so that it could overlap. Any gap was then filled with PU foam.

The overlap was then chamfered to allow in more light.  And all joints foamed and taped.

It's a good idea to take lots of photos so that there is a record for any fixings such as shelves or radiators at a later date.  Remember to write on the wall what you are trying to show - and the location.

This photo records the distances that we will need to know for fitting a curtain rail.

This is just a picture of a the insulation installed with battens prior to plasterboarding.

Half way through plasterboarding and window board is installed.

Plasterboarding the reveals - plasterboard is held by adhesive PU foam.

The overlap was then cut off.

And a skim added.

Top of window detail.

As you can see, once it's all installed you hardly notice and if you weren't told you wouldn't know any different.

Our house had PVC windows almost throughout that were ill fitting and really didn't suit the property.  These have been replaced with new Building Regulation-standard double-glazed sash windows.  The front ground floor bay was the only remaining original sash window and it was in need of some care and attention.

Replacing it wholesale was going to be very expensive and as new sash boxes need to be thicker to hold the larger cavity in a new double glazed window, a lot of changes would have been needed.

We also wanted to retain some of the original features and it seemed a shame to take out wooden sashes to replace them with new wooden sashes.

The final issue was that beneath the windows were the original wooden sash shutters which we through it would be nice to renovate.

This did however mean that the brickwork under the windows would be a 'cold bridge', so the plan was to externally insulate the bay bricks - around 3 square meters.

It was soon discovered during the restoration that the wooden shutters were rotten at the bottom - a consequence of the earth out the front being raised at some point - we'll be dropping the height of this areas and putting in a French drain of sorts.

We have therefore opted to remove the shutters, insulate on the inside and replace the shutter wooden casing.

For the rest of the bay we have opted to have them refurbished with thin double glazing fitted into the original sash windows.  Thin double glazing is pretty amazing stuff as some of these photos hopefully show.

Our window frames are pretty thin so we have had to opt for the thinnest option - 3mm glass, 3mm cavity with inert gas and 3mm glass on the inside. Because of the thin cavity and thin glass, the overall u-value will not be as low as Building Regulations, but it will not be far off.

The process involved:

1. stripping 140 years of paint
   
2. repairing any timber joints and damaged areas
   
3. removing the old glass
   
4. installing new thin double glazing
   
5. routing-out for brush draughtproofing system
   
6. applying putty
   
7. repairing the glazing bars
   
8. priming
   
9. reweighting, cording and hanging the sashes
   

The brush draughtproofing system is pretty inconspicuous unless you really look hard. It's hidden either between the sash frames where they meet at the meeting rail, at the top and bottom and behind the staff beads. You have to look pretty close in the photos below to see them.

In terms of pure cost effectiveness upgrading or replacing the glass in windows doesn't often make pure financial sense - draughtproofing often does but usually on if done DIY.  However there are lots of other reasons in addition to cost savings for having windows upgraded:

• Radiative losses can be reduced improving thermal comfort.  Or more simply, this bay will now not be an uncomfortable place to read a book on a winters day.  Radiative loses are what causes a whole side of your body to go achingly cold when sat next to a single glazed window for a while.
  
• Uncomfortable draughts. Air movement greater than 1m per second is recognised as a draught and of course cause heat losses, but they are also pretty uncomfortable.  Draughts will be reduced both by the brush system but also by reducing convective draughts from cold air dropping down the inside of the windows.
  
• Condensation. Anyone with single glazing knows the downside of cold nights.  As the glass temperature drops lots of the moisture in the inside air condenses and by the morning there is a puddle on the frame.  This can be worse with draughtproofed houses and insulated walls.  The draughtproofing can lead to higher humidity levels indoors if controlled ventilation is not installed, and the wall insulation raises the inside temperature of the walls so they don't absorb as much of the water varpour.  These windows should now be free of condensation.
  
• Noise.  These windows are on the street side of the house and will now be a lot more sound-proof.
  
• Security. The windows will now be a lot more secure.
  

It's quite a specialist job so we employed Ron Bowie of Alexander Restoration. We are thoroughly please with the service and end product. Ron provided a detailed item by item breakdown in his estimate. In actual fact the final price ended up slightly less as some of the contingencies in the estimate weren't needed.  He even left the inside and outside areas tidier than he found them.

We've been making  a lot of effort insulating and sealing up our house in order to save money on our bills and reduce our CO2 emissions....so there is no point punching lots of holes in it in the bathrooms and kitchen....equally we don't want a damp and (smelly) house. One option would be to install a whole-house mechanical ventilation with heat recovery (MVHR) system and another is to install individual room heat recovery units in the key areas.

Both work on similar principals - exchanging heat from moist smelly internal air to the fresh outside air as the first is expelled and the second is introduced into the house. They do this by passing them through heat exchangers.

The system I am going for constantly monitors the humidity of the internal air.  The humidity level can be set for difference rooms.  when the humidty is below the setting the fan runs at its trickle speed of 19m3 per hour and when it is above it runs at 38m2 per hour.

The trickle uses 9Watts (and 21dBAs noise level) and the boost 46Watts (and 45dBAs). They can also be installed in damp bedrooms as they come with a light sensor to stop them going onto boost mode at night.

It's claims are a heat recovery up to 86%.

Essentially the extract unit looks very similar to a normal extractor fan but there is a bit more technical stuff inside - filters and heat exchangers.

We are going to be putting in four.  One in each of the main bathrooms and ensuites and one in the kitchen.

The only other component is the isolating transformer unit that also has the humidity sensor and boost override cord.  This is positioned away from the unit so it can get a more accurate reading of the humidity in the room - useful when the SELV fan is installed in a shower enclosure.


The whole units cost a bit more than a normal extractor fan but a mixture of the savings and importantly having a comfortable damp free house will make it a worthwhile investment.

Running costs
I've estimated that the running costs of the four fans will be around £48 a year if we didn't have a PV system.  With the contribution from the PV system and the fact that the boost Wattage will not be on at night I estimate it will cost us around £27 a year in electricity.

In terms of heat energy, they will of course lead to greater heat losses than a totally sealed bathroom/kitchen but the realistic would be a 0% heat recovery normal extractor fan which would lose a lot more heat. I'll calculate the heat savings over a normal extractor fan in a follow up posting when I install them.

The rear of the house was a bit funny as it had an extension added onto the top in 1994.  This means its part solid brick and part blockwork at the top.  Or put another way, part terrible insulation and part reasonable but not amazing.

And we don't think it is very attractive either.

Another point is that there isn't all that much space inside to be adding internal insulation. So we decided to insulate on the outside.

So first of all the 90mm of phenolic insulation is fixed using a mixture of adhesive and mechanical fixings. This is the pink phase...

Next the whole lot is given its first render coat on a mesh.  The grey phase.  The strange shape is where the extensions are going to be.

The final top coat is then applied - when you have a 6 hour minimum dry period expected.  The pictures below show the almost finished product - still needs the window sills to be installed and the downpipe to be connected.

These walls are now a minimum of 50% better than Building Regulations or about U = 0.2.

What are your views on the blue?  We like it.

Following a slightly leading question from my colleague David, I've done some
quantitative analysis on the potential savings now and under a hypothetical Renewable Heat Incentive regime.  The RHI will now require metered amounts for which I've used the modelled kWh savings from a solar  thermal system over a non solar thermal system.  In reality these may be below the actual meter amounts as these will include any storage losses.

.

I've modelled:
   -  1) an A rated combi boiler  (although the house and number of bathrooms is too large for a combi)
    - 2) an A rated combi boiler with low flow showerhead
    - 3) an A rated boiler with a solar ready 250litre cylinder
    - 4) an A rated boiler with a solar ready 250litre cylinder and ultra low flow showerheads
    - 5) an A rated boiler, solar thermal system and 250litre cylinder
    - 6) an A rated boiler, solar thermal system and 250litre cylinder and RHI payments
    - 7) an A rated boiler, solar thermal system and 250litre cylinder and low flow showerhead
    - 8) an A rated boiler, solar thermal system and 250litre cylinder and low flow showerhead and RHI payments

Not done yet....I've also looked at the paybacks with fuel prices and RHI prices remaining static as well as with a 10% annual increase in fuel prices and a 2.5% increase in RHI payments.

I've applied costs that are either marginal (i.e. for solar thermal) or that apportioned to the hot water (i.e. in the case of a boiler).

And here are the results:
       Annual Saving        Install Cost             Payback                        Payback                        20 year savings
            (year 1)                                        (static prices)        (with prices increases)            (less capital outlay)
1)          £125                    £200                    <2 years                        <2 years                              £6,959
2)          £143                    £250                    <2 years                        <2 years                              £7,940
3)          £107                  £1,000                   <9 years                        <7 years                              £5,071
4)          £146                  £1,050                   <8 years                        <6 years                              £6,853    
5)          £171                  £3,500                  <20 years                      <12 years                             £6,638
6)          £309                  £3,500                  <11 years                        <9 years                            £10,163
7)          £195                  £3,550                  <18 years                      <11 years                             £7,676
8)          £310                  £3,550                  <11 years                        <9 years                            £10,614

A normal house uses around £250 of hot water a year. A normal house could expect to save 50-70% of that with a £5,000 system. The maths isn't hard - 28 year payback at best. The key thing is that the proportion of our energy bills due to hot water is much less than most of us think.  It's also much easier and cheaper to make savings by reducing your demand (less baths, combi boilers, low flow showerheads etc) rather than trying to make you own. 

And once you do this the paybacks are even longer.

That's not to say solar thermal is always way down the list of things to do, and it can be a really good solution for properties off the gas network or where you have a rugby team staying in your home.

So back to the question at hand.  Why am I installing a solar thermal system? 5 reasons really...

1) I'm starting from a situation where there is no heating system (I took out the storage heaters and multi point gas boiler) so installing a solar thermal system in addition to the rest of the work will be a marginal extra cost.
2) I've got a young and growing family and there are likely be lots evening baths (especially when the rugby age arrives)
3) With a super insulated house the proportion of our energy bills that are due to hot water will be relatively large and so achieving our personal ambition to be as low impact as possible means starting to tackle some of those areas usually less worthwhile.  It'll be interesting how long we can survive on solar thermal and the wood burner before the gas boiler gets turned on for the winter.
4) I expect gas prices to rise
5) There is still a chance the Renewable Heat Incentive tariffs - rightly or wrongly - will be set at a level to make solar thermal systems financially worthwhile.

The Renewable Heat Incentive Premium Payment of £300 isn't one of our reasons as it doesn't make much impact.  We do however welcome the decision to gather more data before setting tariffs.

I'll blog a bit more about the details when it gets installed...

There are plenty of super eco-renovations that take place each year with the best of the best installed at top prices (and all to often some gimicks). Often these projects show that amazing reductions can be achieved...if you are willing to pay a lot of money. In many circumstances it would be cheaper and easier to rebuild the house from scratch!

Our emphasis at Parity Projects is to help people who don't have infinite budgets, work out how best to achieve large energy savings and CO2 reductions without costing the earth or over carry out upgrades over time.

Our eco-renovation is being undertaken with that in mind. In addition every cost is being tracked and categorised to the degree of 'eco' it includes.  Examples are the insulation - full eco credentials, wood burner - some eco but some luxury, replacing the inappropriate PVC double glazing with new double glazed wooden sashes - pure indulgency.

We're also carrying out most of the work to the main house ourselves. There are limits to this on the gas and electric sides but lots of the meanial work of electrics and plumbing can be done by us.

By us I mean our DIY team which includes: my Dad - a superstar who can turn his hand to pretty much anything and do it very very well.  He's so useful on the planning and doing sides. My wife - part time labourer, designer, researcher and
more than her share of childcare. My mum - ideas and childcare that lets us crack on. My father in law for advice on the electrics.

The Government launched the Feed In Tariffs last year. This means that householders can generate income from electricity-producing technologies above and beyond the actual savings to themselves.  I'm not going to go into the pros and cons of the actual scheme here but just give some information about my new PV system (that photovolatics - i.e. panels for generating electricity).

Since there will (hopefully) be some building extensions around the house, thus restricting scaffolding, and the internal walls are back to brick (so cabling is easy), we decided to install our PV system early.  Oh, and the summer is here so might as well start generating now rather than in the autumn.

We've gone for nine 250W Sanyo HITE01 panels. These are at the more expensive end of the solar panel range but offer higher outputs per unit area and we don't have the largest roof to play with. The inverter is an EverSMA 2500HF.

To start from the beginning and very basics...
 The panels sit on the roof.  A frame is fixed through the tiles onto the roof rafters and the bolt holes sealed. The panels sit on the frame. The panels are pretty light - our 9 panels weigh less than two of me.  This means that the additional weight on the roof is not a worry.  In actual fact as there is a gap behind the panels due to the frame holding them off the roof there is actually greater risk of lift.  The gap is partially there to help them cool as heat reduces their efficiency.

The picture below is just after 7.30am so shading is not going to be a problem!

The panels produce DC electricity and are connected to an inverter which we have situated in the loft space.  Ours is bright yellow so cannot be missed.  The inverters primary function is to convert the DC current to AC.  It also manages changes in the DC input to optimise the output and records lots of statistics for us.

The output AC current from the inverted travels down to the a generation meter and into a dedicated RCBO on the consumer unit. It could go into its own MCB on an RCB protected side of the consumer unit instead. Don't worry if none this makes sense as the installer will do everything and provided you with relevant certificates before they finish.

We will get paid for everything we generate (~43p per unit), what we are deemed to export (~3p per unit) (deemed to be 50% of that generated) and won't pay for what we actually use of that which we have generated (~13p per unit not bought).

Over the first 9 days I've averaged just under 10kW a day or around £4.50 a day in revenues/savings. We do have very long days at the moment although it has been pretty inclement since the panels went in.

So what can we expect to generate from our system?  Somewhere between 1,850kWh and 2,000kWh or around £1,000 a year in payments from the Feed In Tariff and electricity savings. So now my challenge is to see if I can get our annual electricity use down to near what we will produce.

The first year of the Feed In Tariff was a particularly sunny year and first indications are that most systems significantly outperformed expectations.  My Dad's did by over 30%.
 
Parity Projects independently calculate expected returns for you as part of our Home Energy Masterplans where appropriate.

Here are Andy and Phil from Green Tomato Energy who project managed and carried out the electrical side of my installation respectively.  A job well done.

The main problem with thermal bridging (also known as cold bridging) is that it can cause a focal point for condensation.  This can be especially pronounced with well insulated properties as the treated surfaces remove less of the air moisture invisibly - i.e. condensation in such small amounts that you don't see it.  The cold spots from thermal bridging therefore can have an accentuated amount of condensation which can cause surface water and mould growth.

Heat loss through thermal bridging is usually relatively small - by definition a large area of poorly insulated fabric is no longer a bridge but a normal heat loss element! (caveat - for super insulated houses although the absolute amount of heat loss attributed to thermal bridging may be small it may be proportionally a large amount).

So, the question is, does our house have any thermal bridges to think about?  Well, just a few :-)

I've greyed out the extensions in the drawings below.

1. The proposed side infill will be set back from the road to maintain the streetscape. There the sitting room wall insulation will be continued past the beginning of the infill by at least 1m.
2. The current proposal is to insulate under the bay window on the outside as the wooden sash shutters can then be kept (renovating them is another job!)  As much overlap as possible between the internal insulation and the external insulation where the bay starts.
3. The insulation will be continues along to the fireplace to stop the thermal bridge from the solid party wall.

Please note that the pictures do not show the completed insulation installation. Foaming the gaps, taping the joints and levelled vertical battens are required prior to any plasterboard being installed.

4. Again the insulation is continued up to the fireplaces to allow for the solid party wall conducting heat out.
5. At all the windows the insulation will be continued into the reveal to overlap with the sash boxes.
6. There will be an overlap between the external insulation of the original rear section and the internal insulation in the main part of the house.
7. The adjoining property is one storey lower and so there is a potential cold bridge diagonally downwards into our first floor.  We are continuing the insulation down from the ceiling by around 50cm. An easy one to have overlooked!
8. Again the insulation is continued along the wall to overlap with the proposed infill.

9. The final design of the infill will determine the degree of cold bridging that is present on the flank wall above the infill.
10. The original rear section is slightly shorter than the main building. There is therefore a small area of solid external wall and so thermal bridge below which will also need to be addressed.

Most chimneys, especially in urban areas are redundant.  The trouble is that they still perform one of their primary functions whether they have a fire in them of not - effectively taking warm internal air and putting it outside. At the same time cold air is drawn in due to the low pressure caused by the rising warm air.

End result - higher energy bills and thermal discomfort from draughts.

In the diagram on the left the blue arrows in the loft space indicate a properly ventilated loft which is needed to keep the rafters and joists dry and prevent rot.  The ventilation comes from the eves.

The traditional solution to redundant chimneys is to slow the air movement down by semi blocking off the fireplace openings but installing vents to allow a trickle of air to enter.  The chimney pots usually have a horizontal cover put on them to stop rain entering but still allow air out.

The reason for now blocking off the chimneys totally is so that any moisture that does get into the chimney can get back out. This happens either by penetrating the brickwork from outside or moist air penetrating from inside and water condensing as it cools.

The problem with this solution is that warm air is still lost, just as a slow rate.

We've got 6 chimneys in two stacks.  One of which, on the ground floor north side of the house will be retained as a working chimney with a small wood burner. The wood burner is small enough to not require additional ventilation to be installed.

The other five need some attention. The plan is to totally cap off the chimneys and the fireplace openings but to ventilate the chimneys - essentially sealing the chimneys off from the inside of the house but allowing outside air to trickle through them and into the loft space. The ventilation will help keep the underfloor timbers and loft timbers dry.

The chimneys will be connected by short lengths of pipe, with the bottom fireplace connected to the underfloor void with a small length of pipe.