Wednesday, September 30, 2009

Inverter in Loft

30 Sept : I always like it when people enjoy their job. This is Julian, the electrician putting the final touches to the electrical parts in the loft, under the panels. The Sunny Boy box in the middle is the inverter, and below that are two isolator switches, one for the DC from the Panels, and one for the AC to the meter downstairs.

We have a handheld display unit picking up a Wifi signal from the inverter so we can have that in the kitchen, dining, or even next to the bed - so you can wake up on Summer mornings wondering how much your panels generated before breakfast!

Tuesday, September 29, 2009

Sharp MonoCrystalline

29 Sept : People will want to know which panels we have used. There are cheaper panels but you need more of them, and we have only a limited roofsize for the electricity we want to generate.

The Sharp 180NUSoE3E seems to be the ideal choice, and fits the roof as if it was designed for it (the Velux positioning was designed for it) The spare roof space between veluxes will be ideal for a future Solar thermal flatplate if we decide to fix one.
The NU180, at 1 metre x 1.3 metre is an ideal tile size for using in assessing other people's roofs for their fitness for photovoltaic installation.

PV Panels are up!


29 Sept : The Sharp PV panels are up, they went up incredibly quickly between lunch and teatime on Monday 28th. Tuesday has been a day of fixing the internal electrics, meters, inverter etc. Pity we cant leave the EvoEnergy van parked in the drive, as it would be a good advert for them, seen by all the walkers who pass our house on the way to Sharp Hill....

In the photo, DNC, the EvoEnergy van and the redoubtable Eddie Muriel, leader of the installation gang.

Sunday, September 27, 2009

Scaffolding up for the PV Panels

27 Sept : On Friday afternoon, the scaffolders turned up and did a wonderfully efficient job, getting the whole rear of the house done in just an hour, including building a bridge across the glass conservatory. I nearly reduced the total of panels to a line that would not be above the conservatory - simply because I didn't trust the scaffolders to get this up without breaking one of the panes - how wrong that was!
   The 22 we have ordered will cover most of the roof, offering some space at the south end to add a further 3 sometime, if we are permitted to within the terms of the Feed in Tariff. At the moment our proposed 22 equals 3.96 kW, but only if facing south.
Haha don't worry, the house isn't really bending. It's the Panoramic-Photo effect that joins several pictures together. If the camera is slightly tilted upwards, you get a bending effect.

Wednesday, September 23, 2009

Solar Power in KobnHavn

Sept : I have an architect friend in Copenhagen reading this blog and considering PV on a 6 storey office block he is working on.
I am not sure of the tariff in Denmark,  but in the proposed German style tariff for the UK, it's definitely worth fitting.  So I replied that:
For us as an all electric household in the UK, we have in effect a season ticket for 20 yrs (the guarantee period of the tariff, but this is extendible)

For a one off payment (to Instal PV on our roof), we have:
Guaranteed TWENTY Years
 of NO HEATING Bills
     NO HOTWATER Bills
     NO COST FOR COOKING, LIGHTING AND POWER
On top of which, our roof will earn some money, because we generate more than we need. All we have to do is clean it annually (with a long wet brush) and make sure all the electrical connections are in good order. We will have meters, and can check if there is any falling off in performance due to atmospheric dust etc.
The cost is about the same as a medium size car. In 20 yrs that car will have been scrapped, in 10 year it will be worth not even £1000 and we would need another.
In 10 and 20 yrs, our roof will still be earning money, providing totally free heat, light and power, and if we are still here and had to move, the panels have a resale value, and can be assembled on the next house, or add value to the house we are selling, more than they cost in 2009. The EPC system in the UK will add value points to houses with energy efficient systems.

For his 6-storey Office building, I replied:
There is value in fixing it to a vertical facade, as you get less power in summer, but more in Winter when you need it more. And a wall is more self cleaning - and high enough not to be shaded by neighbours.
Overall though, with the tariff arrangements, its better to harvest more in summer and sell it, but its difficult to arrange that on a facade. For Kobnhavn that would need to be 38º
See this table for 4kW worth of panels... (for your 6 storey you could have a lot more the 4KW. and you do SAVE on the cost of rainscreen cladding, as solar panels do that.)

How close to south can you make the wall? with a NEW building this is more important as you can design it to be optimal, instead of just attaching to an existing wall that is not in the right direction. For an Office building it's good to reduce the amount of South Window, so have more windows to north (for workspace daylighting), therefore have more wall with solar power on the south, reducing solar gain and reducing air-conditioning costs.

Tuesday, September 22, 2009

Solar panels are coming... Recalculate!

22 Sept : We are expecting the scaffolding this week, and the 22 panels to go in early next week.
    I have recalculated the payback at a more disadvantageous rate, to make sure that it still works, and of course it does. Solar Century advise a general split of what we SELL and what we USE as 50-50%. But it's advisable to consider a 70-30% split, because most power-lighting is used in evenings. In a gas heated-cooking household, very little power is used in the daytime (if people at work) so the split could be 80-20%. As we are an all-electric household (albeit with heatpump not direct heating) the ratio improves in our favour as more power is used in the daytime - this could be closer to the 50-50. So on a pessimistic 70-30 basis, we are still well into profit.
    EvoEnergy have also offered to instal better than usual display, so that we can record additional data such as daylight levels and panel temperature (all of which affect their performance).

Monday, September 21, 2009

Meter bore, snore... but it's needed

21 Sept : If one is to research this properly, every piece of data must be recorded BEFORE the PV panels and the Solar GeoCharging are installed, and for the duration of the experiment AFTER they go in.

Ice Energy provided me with an electrical consumption meter for the actual Heat Pump, so we shall know precisely how much that uses, on a weekly basis (They offered me another for fitting internally, but that needs advanced plumbing, so that's for later).

At WEEKLY intervals, I am also measuring the operating hours of the heatpump and the immersion heater and the temperature of the deep Borehole, Domestic Hot Water consumption and total incoming Cold Water supply, and the amount of liquid pumped round the ground floor heating circuit in m3.

The Immersion heater could be disabled, but I don't want to, as the purpose of the research is to see if the Solar Geocharging will make it unnecessary. When it operates, the CoP of the Heat pump doesn't exist - the house is being heated directly from the grid - bad! It has used it for 444 hours since Feb 2007.

I already record the daily electricity consumption of the house. During the summer, this represents the cost of Appliances, Cooking and Domestic Hot Water. Extrapolate this, allow something for winter lighting and you have the annual consumption excluding Space Heating. I don't know the division of  =Power+Light= and =Cooking+DHW= - I am estimating they 2500 and 1750 annually. Subtract from the total of 8500 and you have the =Space Heating= at 4250 kWhr - we shall find out. Most Gas based houses use gas for Cooking and DHW, and their Power and Light are more like 3300.

When the PV is fitted, then there will be daily and weekly readings to record, and we shall see what the OfGem and the EvoEnergy meter will tell us.


I have worked out the consumption when in action and on standby of most of the power fittings in the house. I am not one of those who likes living in a dark or silent house, so we are not going to frantically turn everything off.

Thursday, September 17, 2009

Positioning of Solar collectors


17 Sept : I have done a drawing to calculate precisely the position of the panels on our south wall. I dont want to drill holes through our external wall for 40mm pipes only to find that the holes are wrongly positioned. It's important to make sure that it will fit the attic trusses on the inside. In the attic, the pipes will be fully insulated and run the length of the house, to drop down to the heatpump on the North end. I have to ensure that the return pipe will miss the vertical part of the roof trusses. Also, each pipe needs an airlock release valve.
  In this drawing, the flow is to the outer upper corners of the panels, and the return is from a Tee joining the panels together from the base. It is best for the pump to push the glycol downwards against the natural convection direction (upwards). This puts the panels into a 'parallel' arrangement with diagonal flow through the body of the panel.

Wednesday, September 16, 2009

Wood burning stoves



An earlier posting referred to the idea of a Woodburning stove as another method of heating, in partnership with a solar tank. WBS may seem laughable, as the heat is only in one room, and maybe they get too hot for that room, and they are emitting smoke to the atmosphere. Also, it needs plenty of ventilation, which goes against the PassivHaus idea, which includes airtight houses.

But Woodburning stoves are considered carbon neutral, as they are burning carbon that was grown in your own lifetime, and it is low grade carbon, not the highly concentrated carbon from fossil fuels. Using a Backboiler model, you can convey heat away from the stove to another place to store for later. And efficient stoves can be managed by slow burning, they don't have to burn all at once, they can stay in overnight.
Stoves on Line have a proposal for just this - this is their illustration. This proposal is using a large accumulator tank getting heat from the woodburning stove for winter storage and also from a solar panel for summer. This backs up the domestic hot water, and supports space heating through underfloor heating or low temperature radiators to draw heat from this tank to give the rest of the house. See also BoilerStoves webpage for more detail.
We can't do this to our house, as it would be most difficult to insert a WBS and we don't need an accumulator tank because we have a heatpump and our accumulator is the borehole. But this seems an ideal combination for a newbuild house, or for upgrading an existing house.

Metering an easy way to cut consumption


Good Energy Shop is a good place to get two essential items for the house. One is an OWL meter that measures the total energy consumption of the house, at any one moment or accumulated over time. Having a Display in the house immediately prompts you to hunt down the culprits, eg a light left on in bedroom, towelrail, TV on standby etc. - the hunting instinct pays off! You connect one part of it to your meter cable, and the Display unit is free to position anywhere in the house (wifi connection to the meter).

Some items use power when on stand by, and some items use energy even when turned off (but the socket left on). For individual power consumptions, you need an meter for an appliance. The Brennenstuhl meter allows you to check individual items, eg to check the standby consumption of a TV, to know how much your kettle or microwave use. By measuring the accumulated power, you can see how much a full dishwashing cycle takes, or your washing machine. Smart fridges have various power consumptions depending on what they are doing, so you can zero the meter, then leave the fridge to work for a day or a few days, and find out the average daily use by reading the accumulated power consumption over that time.
I am making an inventory of every item in my house, to check its consumption when off, on standby or sleep, and when on and active.

Yes... I am becoming a meter and switch-off bore in my household, but for the research project, it's important to research the performance of the house and its appliances.

Peveril Roof - BEFORE


I was asked today for information to enable the scaffolder to plan the frame, so sent them 3 photos. This one is good as an illustration of the roof BEFORE the PV installation goes up.

I was also asked what sort of display I want eg a panel in the kitchen/utility to show current and accumulated amps/kW/kWh output. I would also like to know the amount used by appliances in our house, and the amount exported to the Grid. Perhaps that should be visible from the OfGen meter.

Tuesday, September 15, 2009

Mocking up the panel layout


As the Solar Focus panels are new (and untried for this purpose), we did a dry mock up of how the panels would be plumbed on the south wall of our house, using 40mm pipe joints. On the upper wall, we have 2.55m of clear space between the window and the RW downpipe, so need to work out exactly how the panels will fit, along with all the joints, which add 65cm to the width of the actual panels. I am doing an ArchiCAD drawing of the arrangement - the total width of both panels including fittings will be 2.25m, but another arrangement could be to space the panels either side of the window, so that I can reach the air release valve without needing a ladder.

David Atkins mooted the idea that with enough of Solar-air panels like these, you would not need slinkies or borehole at all to support a GSHP, as solar air-panels can be more effective than ground loops, or can be very effective supplements to a reduced cost ground loop, as indeed we are intending to find out.
There would be many variables such as glycol flow rate, and how many degrees of frost the panels can endure, if the GSHP pushes glycol round even colder than a winter's night air. (He has seen collectors encrusted with ice, but safe). As one most frequently requires heat at night, a system drawing heat from a buffer solar water tank (that is warmed in daytime by the solar-air panels) would smooth out day-night fluctuations. It's worth modeling on the computer, if not in real life.
The water in the buffer tank wouldn't freeze, as there comes a time in winter when the GSHP is getting more of its heat from the deep ground (which is 10-12º) and I have never seen the outgoing glycol to be less than -1º for short periods. Ice needs a lot of latent heat to freeze, and then doesn't expand until it gets below -4º.

Roofrack brings home the Panels!


15 Sept : I travelled down to Oxford to visit Ice Energy, and to talk with David Atkins. We debated whether to use a single 1.8 x 2.0m IVT Kompact Kollector panels of plastic piping (which he has already tried out, fixed to a handbuilt metal frame), or to use a pair of 0.8 x 1.35m Solar Focus swimming pool heaters (that he has recently acquired for testing).

We decided on the Solar Focus panels. They are handier to transport and rig, and would be more likely to be used by a householder copying our idea as part of an add-on to a Heat-Pump installation. We do not know whether 2 or 3 or 4 panels would be best, but that is not the point. We are proposing to create a rig and get data from it. If after a full season, it appears to work, but could work better, that is the time to decide if we add 2 more panels - 2 will do as well as 4 for the present purpose.

During the day, I had a short phone discussion with Andy Sheldon, MD of Ice Energy, who has agreed to let me have the panels and the fittings, and we shall be partners with Ice Energy in seeing how this system will work. We are paying the plumbing, electrical and labour costs, and hopefully, the university will provide something in the way of dataloggers.

Sunday, September 13, 2009

News from Down Under


13 Sept : I am grateful that my erstwhile structural engineer colleague Peter Fawcett writes to me from Hobart, Tasmania,

"Charging-the-earth is an interesting idea: I guess the efficacy would be dependent on the local geology, in particular any groundwater flows."

"I have a groundloop heatpump system here, thence into slab coils. The context was right: plenty of space on an equator-facing slope (hence a bit of solar top-up to the ground even in winter) but couldn't go all that deep because of rock. But it seems to work. Unfortunately the Australian market for geothermal is quite small and the only appliance manufacturer with an agent here is the American WaterFurnace. The agent is in Sydney and the technical support in Adelaide - each about 2000km from Hobart!"

"There's an interesting issue of control because of the timelag of the floor slabs, combined with the wide changeability of our weather systems. What it needs is direct input from the government weather-forecasting service to a timer-controller. Meanwhile. it keeps me amused to try and anticipate demand."

"Many other interesting points on your blog. The issues here in Oz are similar but different, if you get me."

Monday, September 7, 2009

Winter and Summer charging ideas


7 Sept 2009: Talking to my architect friend in Cardiff, Alan Gillard, he described how he has used reverse cycle heatpump in a scheme in Wales, that is in effect, charging the earth. Using the reverse cycle, the underfloor heating can be underfloor cooling, so that excess summer heat from the buildings is dumped into the borehole... where it is retrievable in the evening, or in the colder seasons. He knows of schemes in Europe that use reverse cycle this way.
   The last two UK summers have not been hot enough for this to be activated, but its a great idea for hotter climates, instead of air conditioning.

He also discussed the idea of the solar thermal water tank being also a buffer for ground charging in my previous blog article. He suggested that it could be made even more efficient if the tank was charged with surplus heat from a winter / night-time source such as the backboiler pipes in a woodburning stove. So that all year round and in the evenings the tank could be getting heat from somewhere  - (summer=solar, winter=woodburning stove) and that whenever the temperature rises above a target temp like 30 or 35, the remaining heat is sunk into the ground loop to charge the earth - this stops the tank ever from overheating.

A way to reduce Stasis in Solar Thermal tanks?


7 Sept '09: We seem to be far down the road with this idea of hanging the black pipe-grid on the south wall. I did get slightly talked into this, as Ice Energy are keen to see if these will work. So I got talked out of a flat plate panel on the roof, and into using the uninsulated black plastic 'kompakt-kollektor' on the south wall. And the idea is much cheaper to carry out.

I do actually have a planning permission to hang a solar collector on the south wall that cost me £170 to apply for 2 yrs ago! So I am not worried about planning.

The whole purpose of this is to be experimental, but I am disappointed that one thing we are not doing at all is preheating the water - one of our earliest ideas was to do this, and only to throw heat down below as an incidental; we moved sideways, and found a new focus. With the idea of charging the earth, it would now confuse data collection to add water preheating to the mixture.

We all know that one the biggest problems with Solar water heating is that if you don't use a lot of the hot water, the tank and the panel reach a stasis, where no further heat goes into the tank. It just sits there being hot. And we do not use much hot water, and I don't want an incentive to use more hot water. So, what to do with all that heat? Can the heat of the stasis be the heat we pump into the depths?

I am weighing the much earlier idea to preheat water using an industry standard flat plate solar panel. As we use very little hot water, the tank would spend a lot of time in a hot condition. Most tanks are available with two coils, so the lower one is for the solar panel, the upper one is spare. The idea could be to have a glycol loop in that upper coil linked to our ground loop. Whenever the sun shines some heat goes first and only to the tank. When the temperature in the tank is above a defined temperature, say 30º it will trigger the pump to send surplus heat down to the borehole, till another defined figure, such as 25º. In summer, solar preheater tanks get to over 40º so there would never be a chance of wasteful stasis. The water would be delivered to the GSHP at something between 25 and 30, reducing the energy required to heat water up to 51º.
    Although we could not easily isolate the data for the solar charging, we would monitor the overall increase in efficiency, by monitoring as many temperatures and flow rates as is possible - it should be possible to derive some figures for the solar charging. The final arbiter is the annual electricity consumption, which is a measure of the carbon emission. A significant drawback is the embodied energy of a large insulated copper water tank, and then there is the question of how to get it up into the loft.

Saturday, September 5, 2009

Where is this elusive Carbon Zero?

We have entire Zed-Carbon design units and Solar Decathlon projects, and many researchers and professors in our Department of the Built Environment trying to work this one out! The answer is never clear - which is why we keep repeating the exercise every year. And we must avoid answering that it can be done by offsetting (lazy thinking, "leave it all to someone else"). If off-setting works, then we are already Carbon Zero, and we can stop trying.

Perhaps Only the combination of many different ideas.....
• Biomass - Heating with Wood burning stove (to avoid using gas, and wood is notionally carbon zero), and
• 4kW or more south facing PV for the electric (for cooking and lighting and heat reclaim),
• Solar conservatory (get reclaimed heat from),
• Whole house Heat reclaim (from conservatory, cooking, incidental gains etc)
• Heavy thermal mass (storage) and
• High insulation (keep it stored),
• Wind turbine for generation when the sun doesn't shine, and
• The rest of the roof in grass (to replace oxygen)
• Batteries to store excess power, or a connection to the Public Grid (which is a societal cost)
• Bicycle storage, woodshed, potting shed...
......will yield a carbon zero house... through design, not offsetting.

Yes .... if you haven't noticed, we have virtually described the Hockerton houses, except for the wood burning. It takes that level of commitment to get it right.

Plus of course the 'Societal costs':
• Rainwater capture and sterilization to avoid societal costs of delivering water.
• Biodigester to avoid societal costs of sewage disposal.
• Plus enough Land to grow food and a few pigs/sheep/chickens to avoid societal costs of food delivery.
• The Labour to make this land productive.
• Using Public transport and avoiding Automobiles that burn fossil fuel (try horse drawn transport...).
For it to work fully, we are talking about reverting to peasant culture in this scenario.

But this is only practical if you have a large site and are near woodland, and don't mind maintaining wood burning stoves and living a peasant lifestyle, not having a job in a city. It is not applicable to 60 million people in an overcrowded island which took decades of smoke control legislation to clean up the air. The World's population has Tripled in my own lifetime. So wood-burning stoves and free range chickens cannot meet that population rise. 1200 houses are due to be built in the field behind our house next year, and the small amount of woodland that is being preserved nearby would be 'scrounged' of free wood within a week.

The 2016 Carbon Zero house target can perhaps only be possible with a co-existing programme of vigorous densification (retaining green belts and more apartments and district heating, and allowing us to have jobs in cities within walking/cycling/bus distance), and vigorous plantations of trees on land not used for agriculture and essential recreation.

If we did the opposite, the US rur-urban solution and dispersed everyone so they had an acre of personal woodland that would not work because of the fire risks (see Los Angeles), but mostly the ginormous societal cost of all the roads and travel costs to reach them... and the unwillingness of most people to live and labour in this way.

What is a Typical Electricity/Gas Consumption?

I have been trying to find out what is considered a typical consumption. Most houses in the UK (about 80%) use gas heating, which is cheaper per kWh than electricity. The average UK House electricity consumption is estimated as 4,700 kWh/anum http://www.npower-renewables.com/earlshall/index.asp

Our house in summer/autumn is using an average of 11.6 kWhr per day which includes one hour/day of heat-pump doing hotwater, plus electric oven, microwave and induction hob, kettle, computer, router, printer, radio, TV, energy efficient summer lighting and Fridge; plus occasional dishwasher and washing machine.

That would work out to 4,250 kWhr annually if there was no winter heating. A gas heated house would use roughly the same electricity/month throughout the year (plus only the extra winter hours of lighting and a bit more telly).

As most houses are gas heated and gas cooking, our house is managing quite a good figure. Take away figures for our electric cooking and hotwater to do it instead with gas would bring our consumption down to the average for a house of this size, of approx 3,300 kWh/yr.

We know that our total annual consumption is precisely 8,500 kWh/yr for the last 2 years, so winter space heating and lighting is causing another 4,250. That is the figure that we have to 'attack' with our Solar Earth Charging project.

How does this compare with a gas heated house? Moneyforums site calculates the average medium size house annual usage as 3,300 kWhr/yr Electricity and 20,500 kWh/yr of Gas. If that is the case, our 4kW roof installation positioned on a south facing roof would generate 3,300kWh, ALL of a typical electricity consumption for the year, for a normal gas heated house. (Sorry to say that with our east facing roof, we will only achieve 2,800 kWh/yr.)
Most gas tariffs appear to be about 6.5p/kWh for first 2,860 kWh, then 3.5p thereafter. See the Energylinx site. While this is the case, it could be used as an argument against the heatpump, because if gas is 1/4 the price of electricity, and a heatpump's best CoP is 4, the two balance out.

In the long run the UK and other European countries may have problems with the supply of gas from Russia, whereas electricity can be derived from renewable sources, including our own roof. So, strategically, we feel safer being 'monofuel' - based on electricity. We could add more to the roof in the future.

On a pure annual cost basis, if we had a conventional house, our electricity would be about £450/yr on a green tariff, and the gas would be about £850/yr. With the heatpump and no gas, it is £1,100/yr. So even without our roof PV and Solar earth charging, we are already doing better. But we want to do a LOT better.

See What You Can Do site, for advice on saving electricity.

Friday, September 4, 2009

Solar Earth Charging: Programme of Action

As this seems to be a first for domestic property, and isn't a pre-defined commercial package, there is not a known package of components or fast track installation procedure (like there is for the PV roof). So, we are feeling our way a bit here, and developing what is possible and affordable with the help of Ice Energy and colleagues in the Dept of Built Environment. We need time to work it through, and to source the kit that is needed, plus the kit for monitoring, logging etc.

So I am suggesting this programme:

1. DNC to visit Ice Energy to collect frame and the compact collector (and some sundries that they will help us with, such as valves, meters, strainer), transporting back on roofrack. During week 14-18 Sept.

2. Fit the frame on the South Wall, including the collector, dry. We shall have scaffolders here before the 28th Sept for the Solar PV panels, and I can pay them to do a platform for the south wall. Fit it early October.

THEN...

3. Work out exactly where to drill holes in the wall, and run the pipes horizontally - a straight run, the full length of the house, at floor level in our loft to a position above the GSHP, still dry. Mid October.

4. Extending the pipes down to GSHP, fitting expansion tank in loft, Valves, Strainer, flowmeters, temperature display, strainer, pump etc. many of the devices in the store above the staircase. Insulate pipes in loft to prevent condensation.

5. Final teeing in connection of the new loop, with the non return valve etc. and filling with extra glycol. Final insulating.

6. Get it running, but make sure displays and dataloggers etc are working.

Perhaps this all done by early November.. too late to get much solar heat down into the deep ground, but never mind. Its as fast as we can do it - and the south wall does get sun even in winter. Because we will be getting into winter, the final connection and glycol filling needs to be done quickly.

Payback... or Payback... which is it?

The moment you mention solar panels or any other green initiative, people ask about Payback. But if they are taking a holiday abroad, or considering a change of car, they never consider that those expenditures can also be considered in terms of payback - in economics it is called Opportunity Cost. A car that gets you to work more reliably than a cheaper banger, or enables you to get a job a further distance away is opportunity cost - by existing, it enables you to increase your 'revenue'.
  There is also the concept of Compounding. If something is increasing by 2% annually, it will double in 35 years. An income of £1200 indexed from 2010 at 2.5% will be well over £2000 after 25 years and will cumulatively have added to £41k not the £30k you expected.
And some things, we do not need payback, we just do them for Quality of Life reasons. Bicycling to work or the railway station is better for health than using a taxi.

Now on our PV installation, the payback is 12.5 years if prices stay level (would be shorter if we had a south facing roof). The reality we all know is that over 12 years, prices of purchased electricity will only go up. If the Feed-in-tariff is near enough pegged to the average purchase price, then our payback time will shorten with every price rise. On a Compounding basis, every rise in Gas prices will also speed up our payback as the alternative to the Heatpump would have been a Gasfired condensing boiler with radiators. The contract for the feed in tariff is for 25 yrs for PV - so what will the cost of electricity be in 2030 or 2035?

The next aspect of Payback is Capital Return. In West Bridgford, the standard bargaining unit of currency in house prices is 10 grand - with some final subdivisions to 5 grand to close the deal. House prices rise and fall arbitrarily, eg the opening of a good new school nearby, or the opening of a Sainsburys, a road widening. Another aspect of house price is the EPC, the Energy Performance Certificate, and the HIPs, home information packs.
   In future, a house with an A or B energy rating will be worth a LOT more in valuation than an older unimproved house.
   If future Council Tax assessment is linked to the energy rating, the payback will be even quicker. Buyers who are conscientious would rather buy a house where the hard work of going green has already been done, than to face the costs of converting a house themselves. We are reasonably happy that providing we live here a few years, the house value will overwhelmingly provide enough capital value payback to meet our spending on the Photovoltaic panels. If the next purchaser would not recognise the value of the panels, it is actually possible to have them dismantled and moved to the next house.
   But meanwhile the panels will earn approx £ 1200 a year, compounding... that's nice too!

Thursday, September 3, 2009

Carbon Zero houses

The government declares that all new houses can be Carbon-Zero by 2016. I dont believe such as thing as Carbon Zero house can exist unless you go to the extremes of a scheme like Hockerton housing, in North Nottinghamshire - who provide excellent courses on carbon zero design but who use tricks in their book that normal house builders cannot use.

Our house has been Carbon-Zero since it was built solely by 'sleight of hand' because we buy our electricity from Good Energy - who only procure Wind Power and other renewable sources. But Offsetting is a trick like Carbon Trading, and as an architect seeking truth, I don't 'buy' it as an answer for all new houses, unless the whole country is able to switch to wind power.


Can we do it? If we upgrade our roof to the maximum with PV (which is 4kW), and even if we had a south roof, this would improve performance by 1500 kWhr/yr (half of its annual production). We hope to reduce our electric consumption 10% by using Solar Earth Charging, but what more can we do? We already have the best insulated house in West Bridgford, we have an efficient modern heat-pump that draws heat from the soil with a CoP of 3-4. The only thing we did not fit was a Heat Recovery system, which is one of several technologies we can use. MVHR will save a small amount of heat, but will burn yet more electricity and makes the house stuffy. We tried a full size Rainwater collection tank; this is good but doesn't save energy quantifiably. We had a planning application turned down for a Wind turbine, but this would have been able only perhaps to make 500 kWhr/yr. One fixed to the house would produce negligible amounts and shake the brickwork, and a more powerful one on a mast in our tiny garden would overpower the neighbours. We already grow vegetables. We cant keep a pig in the back as it would turn the garden into a mud yard, and what would we do with an entire pig when it has to be turned into meat? We have no pond to grow our own fish in, like Hockerton.
It seems that we shall be 'carbon zero' only thanks to the favourable Feed in Tariff on our PV roof. If anybody has further ideas on what one can do with a house in West Bridgford, please advise!

Please join 10:10

10:10 is a mass movement, to get folks to do some self discipline about saving energy, reducing foodmiles and doing anything else that will help the planet. http://www.1010uk.org/
In our case, 10 percent is what we hope to save with our solar charging, and of course a lot more with the PV roof. Its supported by many organisations, most visibly the Guardian... but I see that even the Sun is supporting it!
10:10 is also about a sort of discipline.. cycling more, walking more, growing more food. Even if it doesn't help the planet literally or measurably, it will make us improve our lifestyle to be more healthy and less consuming.
One of the things you can do is buy an OWL meter, so you can rigorously check the amount of power you are using on a daily basis.
PLEASE Go to the 10:10 Web Site and Sign up... and make your decision of the ways you might cut that 10%... or 20%. Its gotta be more than replacing a few light bulbs.

Wednesday, September 2, 2009

PV on Walls or Roof?


This handy Photovoltaic calculator is a great research tool for 'What If?' calculations.
For example, a flat roof is very good over a whole year, if you accept worse performance in winter, but months of excellent performance in summer. (You would also have to consider dust laden rain falling on the surface leaving patterns, and so on, but theoretically it works, and the panels can be tilted to the south. If South Facing only, then undoubtedly, 36º is the best angle for Latitude of 53º north. But I was surprised to find that for an east facing roof, a 10º pitch is far better than a normal pitch because it gets better south and west sun. (makes me think of all those shallow pitch portal frame sheds in industrial estates). Wall mounted panels give acceptable performance with a more even spread of power delivery through the year, but falling off alarmingly if you haven't got a good south angle.
I have a friend who is due to build a house and it is going through Planning. She would like it to be green, but its present design doesn't have any South Facing roof. Even if the payback argument says not to instal this year, what about in ten yrs time when higher electricity prices and cheaper panels make the payback very good? I contend that if we are the slightest bit green thinking, we all MUST build with enough south-facing roof to accommodate at least 4kW of capacity, for future occupants to install.... (but the payback argument is better than it will be for the next 5 yrs).

Photovoltaic Calculator


Aidan of EvoEnergy has pointed me to a marvellous site on the European Commission Joint Research Centre site, enabling calculation for performance of Photovoltaic panels at any angle or azimuth anywhere in Europe or Africa. This takes into account effects due to temperature, reflection, system efficiency etc. It is good for roofs, walls, and even for motorised panels. It will calculate the optimum slope for a given azimuth at this latitude (the best azimuth is obviously from 10 to -10 around south.)
For my Tall Building project I can see that it is very useful for calculating PV panels on Facades. (click on images to enlarge). On the calculator map you can zoom down to a specific town or even street.

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