Parameters:

The choices I have made have been based on the best information available to me at this time, the current situation i.e. no gas / south facing roof and the overall aim of “sustainability” not necessarily cost effectiveness or economics.

In addition some of the technologies are in excess of requirements due to the “showcase” aspect of the project but the thinking that I have applied to the project may be useful to some.

PLEASE NOTE: These ARE my opinions and relate specifically to my situation / location … your ideal solution may be completely different to this but some of the basic principles do apply across the board. You will need a “renewables expert” to come and conduct an onsite assessment to see what will work best for you.

WE ARE STILL UNDERWAY WITH THIS ECO-BUILD AND THINGS MAY CHANGE AS THE PROJECT DEVELOPS AND TECHNOLOGY ADVANCES OR IMPROVES ... WATCH THIS SPACE FOR UPDATES ...

Technologies adopted and reasons behind them:

Solar PV:

Actually installed for the good feeling it gives me to go and look at the amount I have generated every day. Maximum output of my 10 panel system to date is a maximum of about around 10kWh in a day ( and a best average of 80kWh in a 10 day period ). I am even achieving about half of that on a cloudy day with good ambient light. I am, however, going to relocate 2 of my panels as one of my big oaks casts a shadow on them from about 14.30 hrs onwards … and as the panels are in series it effects the efficiency of the whole array. I hope when I have addressed this and we get to the peak of the summer it will generate even more. The systems peak generating rate is around 1.8 kW so I hope to have better figures once the shading problem is fixed.

The electric company are paying me 12p for every unit I export ( Scottish and Southern are now paying 28p !! ) but it is hoped that this will change to up to 35p / kWh “exported” when the governments new feed-in tariffs are introduced – hopefully in April 2010.

In addition to this the Electricity companies also pay up to £47 for every ROC ( one Renewable Obligation Certificate = 1mW i.e. 1,000 kWh ) that you generate if you let them act as your agent with Ofgem. The power companies are obligated to generate up to 10% of all their electricity from renewable sources and they have not been able to increase their own renewable generating capacity sufficiently to avoid heavy fines so you do have the option of acting as your own managing agent and selling your ROCs on the open market . This is a slightly complicated process but ROCs have been known to change hands for up to £300 a time if you have the patience to shop around for a buyer.

Solar Thermal:

Probably the most efficient and best single contribution I could make to my overall efficiency equation. Energy direct from the sun straight into the hot water tank. At times more hot water energy than you need ( you can chose what to do with this but we have chosen to have a towel rail system to utilize excess solar energy ) and we have found a way ( see below ) to use it for hot water and under-floor heating.

The average house can expect up to 80% of its hot water / heating requirement to come from the right sized solar thermal system but it does need some back-up for the days when the sun is not shinning enough for you to get the tank up to temperature - this can be gas ( if you have it available which we don't ) or Biomass ( see below ) or air source heat pump ( a ground source heat pump is not a sufficiently high end heat source to get you up to 60 degrees plus which you need in your hot water system ).

Rainwater harvesting:

A no brainer this – I have directed all my rainwater into a holding tank ( with a filter on it ) and will use it with a small electric pump for watering the garden and washing the car. It is possible to use it for flushing the loos and supplying the washing machine BUT you need to be aware of the risks of storing and using untreated water and have a back-up system in case it doesn’t rain for a while. We

have chosen not to do this but have left the option available to us if we want to use it for this later. Of course we have gone for the 2 stage flush toilets with reduced water capacity to try to reduce our general water usage. We are looking at other ways to reduce water usage i.e. appliances that use reduced water capacity. In the end I hope to have a whole water treatment plant that could take the rainwater right through to drinking water - but that is a way down the road at the moment.. in April 2010.

Biomass Boiler:

This is a groundbreaking biomass boiler from Grant UK who have been in the boiler business with a superb reputation for more than 30 years. This product has been in development for a long time with extensive trials across Ireland and the UK to make sure it is as efficient and effective as a gas or oil boiler. It runs on pellets which you can buy for around £2.20 for a 10kg bag from the likes of Travis Perkins and which in normal usage

will last about 3 days. It is a condensing boiler so it is very efficient and the hopper which you can see alongside the unit delivers the optimum number of pellets to the boiler for its required rate of burn. It is so efficient that it only produces a minimum quantity of ash ( requiring clearing once every couple of months ). The hopper will hold about 2-weeks worth of pellets but you can buy a much bigger hopper to feed the system enabling the boiler to run almost unattended form months although you do have to take care to maintain the humidity of the pellets as this is crucial to the efficiency of the burn.

I have seen this boiler in operation and it does everything it says it will do. The start-up sequence is automatic and takes about 45 seconds to a minute which is fine if you have a thermal store to buffer your water needs and the burn down period is about 2 minutes ( after demand has ceased ) after which the boiler purges itself to ensure a clean start the next time it fires up. Operating temperatures are very good ( on a par with gas ) and the cost of the fuel obviously makes this one of the most attractive high end heat sources on the planet. Mine is due to be installed in the next few months and I will post feedback on its outputs when I have some data available. Anyone interested in the boiler can contact Grant UK on 01380 736920 or visit www.grantuk.com

Air Source Heat Pump:

This is really a "backstop" option for me as I am hoping that my Solar Thermal will be the primary source of heat for me and the Biomass will provide the secondary source. This Grant UK Air Source Heat Pump is actually a bit of a luxury for me BUT is also one of the technologies I really want to study closely so I am going to add one to my system in parallel with the Biomass with a controller that will only call up the Air Source if the other two sources cannot deliver the heat required for some reason.

The Air Source works on the basis of extracting heat from the air ( like a fridge working backwards ) whereby it compresses it and uses a refrigerant to transfer the heat to a heat exchange mechanismin your thermal store. They can work at airtemperatures of as low as -25 degrees and are very easy to install. They are one of the cleanest ways to generate heat ... with a slight condensation when the pump goes through its cleaning cycle onceevery 24 hours and the cool air output requiring you to place it on an outside wall with some free air around it. It also requires about 6 inches behind it to allow the air to circulate. Although it obviously needs electricity to run it the efficiency ratio can be as good as 3:1 when the air temperature is reasonable outside. My preference for the Biomass is solely my desire to keep the overall background energy use of the house ( electricity in my case as I do not have gas ) to a minimum - otherwise the Air Source would be the simplest solution. Anyone interested in the Air Source Heat Pump can contact Grant UK on 01380 736920 or visit www.grantuk.com

Thermal store:

At last I have found a cylinder that will do what I wanted. My challenge has always been to integrate the various number of heat sources ( Solar Thermal / Biomass / Air Source ) with the two main outputs I require namely the under floor heating and the domestic hot water. Up until this moment everyone has been telling me that it cannot be done until Grant UK brought out this Thermal Store. With a capacity of 400 L and up to 5 inputs and 3 outputs the tank acts like a store for the heat. The Solar Thermal runs though it as a coil and exchanges the heat from the Glycol mix to the water inside. The air source and the biomass can apparently put their hot water straight into the tank and mix it with the rest.

The tank itself is stratified which ensures that the hot water ( for domestic high end heat ) stays at the top and the cooler water and return feeds come back to the bottom where the under floor heating can be pulled off from and be mixed down to the temperature of required by the manifold system. The domestic hot water is not actually drawn off from the tank or derived via a coil but benefits from an "external heat exchanger" which will ensure that mains cold water pressure can be fed through the plates with water as hot as 85 degrees from the cylinder on

the other side and derive sufficient heat to supply baths and showers ( say 45 degrees ). This has the added advantage that the cylinder can be a sealed system ( with an expansion tank ) ruling out any problems with Legionnaires Disease ( a risk at under 65 degrees ) and at the same time ensuring that the maximum solar gain can be attained from the solar PV when it is in operation.

This as far as I am concerned is the PERFECT SCENARIO and I have seen the system working in the Grant UK training facility but have yet to install it here. I will update these pages when I have had some experience with it but for now it looks like being the perfect energy solution for my house. For more information on the Thermal Store and the other ranges of Grant UK cylinders call 01380 736920 or visit www.grantuk.com

Insulation:

We have done as much as we possibly can with the U-value of the house – with insulation in the roof / floors and double glazing throughout. We have chosen not to use triple glazing as there is no-body in the UK that makes it ( carbon miles ) and the pound is really weak so it is very expensive. We are applying cavity wall insulation under the current grant scheme to the old part of the house and have cut down the points of ingress of cold air to a minimum.

Low energy lighting:

I have opted for a brand new / very low energy LED that works at 10w ( giving a 50w equivalent light ) but has overcome the old LED problem of a narrow band of the light spectrum and casts a very warm white light. It is totally dim-able and runs on a 24v system ( requiring mini step down drivers to feed them ) not cheap but the most cutting edge solution that I can find ( it comes from the super-yacht industry ).

Low energy appliances:

Miele are now being joined by others in the production of super A+ low energy appliances. Steam assisted ovens / combined washer / drier that recycle the unused heat and highly efficient induction hobs and even an induction wok that help to reduce the overall energy footprint of the building.

Water purification + softening:

At a reasonable cost I am installing a water softener that will reduce the risks of calcification in other areas. It also has some beneficial aspects for bathing for those with skin conditions and is nicer for drinking. The purification is a separate mater and that is me and my paranoia not wanting all the junk the treatment process puts into our drinking water – I want that GUNK out !!

Under-floor heating:

The best way that I know of heating the house. Actually under-floor and “in-walls” to solve some surface area problems we have in certain areas. Very impressive calcs done by Pure Green Energy ( Danny Fisher et al ) that show that we actually need much more pipe in many more places than we initially thought But still one of the nicest heats there is and totally controllable with any number of programmable zones. We will have an interesting time fitting it as we have 3 floor types between the new build downstairs section the old downstairs ( solid concrete floor ) and the timber upstairs ( retro and new build ) so the levels of all of this and the insulation we can use varies. We are covering it all in Warmawood engineered Oak flooring ( recommended as one of the most stable for under-floor heating available ) or natural tiles in the kitchen area which are more suitable there.

Wood-burning stoves:

I have two wood-burning stoves which live off the dead-wood produced from my woods. They do not have back-boilers BUT they do produce a lot of “space heat” which helps to warm the house and the cockles of my heart – I love a real fire and the process of gathering the wood.

Conservatory:

I have a conservatory which generates a great deal of heat in the summer and I cycle the air into the house in a passive way – through a big door and up the stairs ( as heat rises ) – closing the door when the conservatory cools at night. Some people have taken this a step further than me in that they are using ducting to move the air around the house – I will see how their system works and may adopt this from mine in due course.

Raised Vegetable beds:

Just a token gesture to sustainable eating – but it will be lovely to eat home grown veg from teh 6 raised beds that we have now installed.

Coppicing woodland:

Clearing underway and 100 trees planted ( 60 of which have taken ). Am looking now at a fast grow species ( willow / hazel ) that will enable me to feed the wood-burners and might even provide fodder for the Biomass one day.

Technologies NOT adopted and reasons for that:

Ground Source Heat Pump:

A viable option ( either vertical or horizontal ) in most circumstances BUT do involve large amounts of pipe / lots of refrigerant / quite a large pump and heat exchange system and quite a lot of electricity to run them. The water they produce is not very hot and they have been known to cause deep freezing ( or permafrost ) of the ground if used continuously in a small area which stops them working. This can be rectified to some extent by taking surplus energy from the Solar Thermal and pumping it back into the ground as a heat store BUT this is complex and not applicable in my situation as I have exclusion zones in my garden which I cannot lay pipe over.

Wind turbines:

All the indications seem to be that these are not hugely efficient or economical in most domestic installations. Unless you live atop Brightstone Down in completely undisturbed wind ( from all quarters ) and can afford to put a large one up and are prepared to forget about all the carbon used up in making the concrete to secure it then I am not sure it is the best solution. They also have some quite specific wind thresholds and most need about 11 / 12 mph to work well and then some of them have to switch off in winds of over 30 mph. They also have to take 3 minutes to synchronize with the grid so in gusty conditions they may not even synchronise before the wind dies away again - so they may not generate constant electricity at all. Plus at the moment they are really expensive ( +£25k for a reasonably sized version installed ) and can also be badly affected by turbulence.

Combined Heat and Power plant:

Not really suitable for my domestic application tend to suit larger installations.

Grey water treatment:

Options include a grey water treatment plant ( expensive / high energy use but does produce very good water ) or reed bed treatment which I may adopt at a later date if the sewage plant at the bottom of the hill gives up the ghost when the electricity goes off !!

Geothermal:

As far as I know I don’t have any gushing hot geezers near my house.

Hydro-electric power:

Although I do have two small streams that run through the property they do not hold enough water fro this to be viable.

Technologies I most want to try:

OFF Grid with electricity storage:

The two people who I know who have done this have both subsequently come back on grid. The current technology revolves around a room full of sub-marine batteries with the obvious cost / management and disposal of them when they come to the end of their life ( can be as little as 6 years ). Until storage via Hydrogen Fuel Cells becomes a real possibility it is unlikely that I will adopt this BUT as soon as they are I definitely aim to go OFF GRID … by then there might not be much of a grid left to rely upon !!

TRACKING Solar Array:

I REALLY want to know what difference it would make to the efficiency of a 10 panel array of solar panels to be able to track the sun from morning till night in an un-shaded area. Apparently the Germans have developed a turntable system with panels that will tilt in the vertical as well so that using a photo-sensor unit the panels can be kept at the optimum angle to the sun all day … indications are that this might improve the overall output and efficiency of a 10 panel array by as much as 30% - hurrah !!

SMART box to run the hot water and heating:

Developments are underway at the moment to create a smart box of tricks that can operate a mixture of water sources and determine the most cost effective ( or carbon efficient ) one based on the current technologies available. This would ensure that the most effective / efficient of the biomass / solar thermal / air source was being employed at all times. Grant UK are working on this as we speak and apparently a German company has developed this already although I have not tracked it down yet.

Prepared by David Green of 3greenlights.com owner of the “GreenHouse” and host of the GREENtank.

Email:     dgreen@3greenlights.com            Tel:          01983 299886                         Mob:       07786 228722

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