We've just received the results of our Superhome
assessment. Essentially in order for you to be a Superhome you need to have made physical amendments to the property that result in its CO2
emissions being reduced by over 60%. You also have to agree to open it up for tour a few times a year.
Happily the modelled savings show a 77.6% reductions.
This is slightly differently from what I estimated - 83%. Looking at the results in a bit more detail shows that the main variances are in the lights and appliance and hot water use. Our modelling using the Home Energy Masterplan has lower figures in the initial case based on our proposed use for these. The software used for the Superhomes applies standard use.
The Superhomes process also estimates that for our 'after' position, 50% of our CO2
emissions or 2.4 tonnes a year will be due to electrical lights and appliances. This around to around 4400kWh a year (before PV contributions taken into account). We're hoping to be around 2,400kWh based on our actual use.
Finally, the PV contribution is a little conservative at -0.95 tonnes, when we actually achieved just over -1.1 tonnes.
To be honest that's all a little nit picking and as the Superhome software is actually designed to exclude how we are actually going to use the house, i.e. its for benchmarking, it definitely isn't a criticism of the software.
Remember my rough estimate of the additional eco elements of our renovation (i.e. taking out those bits that would be needed in a normal renovation) came in around £22,500. I think 77 to 83% CO2
reduction for that is something to be pretty proud of. Perhaps I'll enter us for some awards in 2013...
Of course we could have gone further and aimed for 90% (and may not have got it) , tried to achieve Passivhaus Standard in a retrofit or similar and spent an additional £XX,XXX in the process. We didn't want to do that though because:a) Why spend £100,000 to get 85% when you can spend £25,000 to get 80% reductionb) The embodied energy of the additional kit to get that little bit more might not justify the potential extra 5%c) We wanted to demonstrate something that is achievable by most people as they do up a house
So how should most people go about it? We'd recommend you start with a Home Energy Masterplan
We've been keeping costs down with concurrent or simultaneous works. As discussed in the previous blog, we had a wood burning stove installed. An incidental cost of this is for the scaffolding. We therefore managed to get a number of jobs that required scaffolding done at the same time - external painting of all the front external windows and window reveals and having the whole of the front re-pointed. It just takes a bit of effort juggling contractors!
Re-pointing is not just important for aesthetic reasons. Its also important to protect brickwork and is even more important with insulated walls. Traditionally pointing was lime based and essentially sacrificial - its a lot easier to re-point than to repair bricks. Lime based mortar draws moisture out of the brickwork and will gradually get damaged and crumble away, especially during very cold snaps. The bricks are kept dry and importantly in one piece. Pointing that has been replaced with concrete based mortar tends to be harder and less porous than the surrounding bricks or stone and can have serious consequences. This is often seen with porous stone where the mortar remains and the bricks or stone have eroded significantly.
As mentioned, its even more important with insulated walls as the walls are colder and so will tend to hold more moisture during the winter.
We've just had a wood burning stove installed. It may turn out to be a bit of a luxury item but maybe not. To begin with we'll have to restrict its use to when there is adequate full eyes on supervision with our two little boys so maybe it'll be limited to evenings and weekends. We opted for a MORSØ Ø4. Importantly it's DEFRA approved for use in smokeless control areas. Its heat output is low at 2-5kW but we're hoping our heat needs are also very low! Its also got a stated efficiency of 81% (although this isn't all that useful a figure).
We had a new flue liner installed and the chimney backfilled with Vermiculite around the liner.We had it on a couple of days ago (end October) and it took the room up to 24 degrees. I haven't ordered a log delivery yet as need to get the patio down and log store built, but there are plenty of suppliers who deliver wood wholly sourced from Surrey, Kent and Sussex.
Preparing the ground.......................installing the plate..........................laying a new sub hearth.........a view up the chimney
From this.... to this... ...and in action.
From right - Peter, Josh, Fraser and Andrew from Sustainable Fires
who did my install.
The house was recently featured in September edition of the RIBA Journal
Parity Projects recently completed its second demonstration retrofit on a newly purchased Victorian semi-detached property in South London. Parity’s first demonstration house focussed on installing and testing a wide range of different and innovative measures, with a view to understanding their practicality and performance. In contrast, the more recent property was intended to be a more realistic retrofit, using measures that could be easily applied in homes up and down the UK. Since the house was also in need of a wider refurbishment and extensions were planned, the project also presented an opportunity to see how the “marginal cost” of improving its energy performance could be minimised through taking a genuinely integrated and thoughtfully sequenced renovation.
As always, the project was started with a detailed analysis of the property using Parity Projects’ Home Energy Masterplan assessment tool. Masterplans, unlike many similar products in the market, are designed to account not only for the physical details of the property, but also the lifestyle of its owners and their household. Taking this approach, Parity was able to identify in advance the most cost effective measures for reducing both the energy bills and the environment impacts associated with the property, and avoid the potential to waste money on inappropriate measures. We wanted to show that significant energy savings were possible without the usual eco-renovation price tag. In that vein a significant amount of the work was carried out DIY
Aside from standard upgrade measures, all the walls were brought up to around 40% better than current building regulations through a combination of internal and external insulation. A tricky side wall was actually dealt with by enclosing it and it is planned to keep it as an unheated buffer area in the winter.
A whole range of heating options were evaluated from heat pumps to biomass. Due to the very low predicted heat load, by far and away the most cost effective solution was a gas boiler central heating system with radiators. This has been optimised by zoning the house into four individually programmable and thermostatically independent zones.
Taking out the cost that would have been incurred in a standard renovation, the overall marginal element of the fabric and heating system eco measures is estimated at around £10,000.
In addition, photovoltaic and solar thermal systems have been added at a marginal additional cost of £12,500. The renovation is also expected to see an 83% reduction in the carbon dioxide emissions from the house, and a £2,250 reduction in the running costs - £1,000 of which is from Feed In Tariffs. Proving that energy-led renovations are not just about saving money, a recent survey of the property has estimated that the renovation has also increased the value by over 40%.
A mini post about our installation's performance in its first (not such a sunny spring and summer) year.
Our PV installer provided the following predictions: SAP - 1,858kWh and PVSol - 1,962 kWh. In the end we actually generated 2,111kWh so 14% higher than SAP predicted and 8% higher than PVSol.
Based this year's Feed In Tariff figures we can expect to 'earn' (made up of FIT payments and savings from reduced imported electricity) around £1,130 in the next year.
Our usage figures for the first year aren't worth discussing much as it was essentially a building site. Around 450kWh was used for lighting, power tools, cups of tea and a few days when my dad stayed on the site in January with an electric fan heater. The gas was switched off. (This essentially means that the build was Carbon negative in terms of on site primary energy use - purists will have a field day with that tongue cheek claim :-) )
Here is a little gadget that is saving some money for some people with PV systems that generate more than they are using during the day. For a while there have been PV add -ns that send some PV generated electricity above set generating levels to the immersion heater. This one goes further and actively monitors your generation and your current use and sends the difference to the immersion.
The key to the amount you save is dependent on a) the fact that before smart meters you are getting paid as if you are exporting 50% of your generation amount whether you do or not b) the efficiency of your normal hot water system and cost of its fuel. In terms of pure CO2 savings in most circumstances it will be better to export it, in which case your neighbours use it and a powerstation somewhere can turn down their furnace a bit. Transmission losses will also be saved. It's the altruistic option but for some CO2 is what it is all about. For my situation, where I have a solar thermal system too, its not useful. A system that diverts to a battery store is however an option.
To help us keep our bills down we're obviously installing low energy lighting throughout. In most rooms this means compact fluorescent lamps and in the kitchen and bathrooms it means 4.5W GU10 LEDs - equivalent of a 40-50W halogen in light output. These were £7 each and we are very happy with their light quality.
As LEDs improve and get cheaper for standard bulbs we will convert to them but they aren't quite there for lights that aren't on a lot..
The picture shows a new LED bulb for a standard bayonet fitting. Its equivalent to a 75W lamp and is a similar light to a standard incandescent lamp when on. We've got one of these for our hall as it can be pretty dark and has a lot of traffic. At £35 its a bit of an experimental toy for me though.
So what did we go with for our heat source? Biomass? Heat Pumps? Geothermal? Trombe walls with rotating phase change thermal drums (a wild idea from my past!)......
Well, after lots of analysis, it turns out that the best option for us is a top efficiency gas boiler and radiators, with some good controls. Why is that? With a super insulated house the heat losses are predicted to be pretty tiny - 5kW heat load in the depths of winter. Hopefully with two boys running around the heating won't have to be on very much. Therefore any savings will take a long time to pay off - far longer than the life of any heating plant. A combination of capital cost, annual running costs and fuel prices means that a radiator system with a gas boiler wiped the floor with other options - in our circumstances.
It's not just a standard installation though as explained below.
The high efficiency condensing boiler is around 90% efficient. It's also going to provide some of the hot water when the sun isn't shining.
The house is three stories and the ground floor has a large south facing area and a large north facing area. We therefore decided to split the house into four zones, each independently time and temperature controlled.
This is done using zone control valves for each zone (there are five valves in the picture as one is for the hot water cylinder).
The four zones are 1) the south facing kitchen extension 2) the rest of the ground floor 3) the first floor bedrooms and study 4) the second floor bedrooms and bathroom
Each zone has a programmable thermostat. This means each zone can be set up to demand heating at different times and to different temperatures - no point heating the bedrooms during the day or downstairs at night. There is the ability to set 5 different heating times and temperature for each day. There are various functions such as 'keep it at this temp for X hours', 'turn onto frost setting for 13 days whilst I'm on holiday and revert back to normal heating the day before I return'.
Because each is hardwired back to the master control unit, I have the opportunity to link the master control unit to my PC and use a piece of software to amend heating programs.
The big shame is that there are very few providers or mutli zone heating controls. Most of the big names just provide a controller for 1 zone. We've actually used a Heatmiser system that is originally designed for underfloor heating installations.
By the way. the picture shows the actual temperature on a summers day rather than my demand temperature!
The radiators and (TRVs)
The radiators look like this for aesthetic reasons rather than efficiency. Each radiator was sized based on the expected maximum heat requirement for each room. Because of the super insulation this means that they are all pretty small. The savings in number and size of radiators was pretty similar to the cost of the wall insulation!
Some of the radiators also have thermostatic radiator valves where they are not in the vicinity of a programmable stat.
The wood burner
We have plans to install a DEFRA approved stove in the sitting room. In most circumstances a wood burner won't contribute much, but even a 5kW one could provide most of our heating - albeit in one room. It will be a bit of an experiment to see how much of the 'shoulders' of the heating season we can solely use it and how much the heat from it will circulate around the house. Savings are not however expected to pay for it anytime soon though.
The final push to get the house ready to move in meant my blogging took a back seat! Having a second baby in tow and a lot of work on for various LEAF projects didn't help either. We ended up moving in at the end of May, into an unfinished but very happy house! I'll continue blogging about things I've done, as well as how things are performing over the following months.
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:
- stripping 140 years of paint
- repairing any timber joints and damaged areas
- removing the old glass
- installing new thin double glazing
- routing-out for brush draughtproofing system
- applying putty
- repairing the glazing bars
- 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 only 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.
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.