Our Budget Eco Bungalow
Posted 17 January 2014 - 09:24 PM
Im Rick, an with my wife an 3 year old son am about to begin that long painful process of building / project managing our new home.
We have been lucky to be given a 15 by 30 plot, from my family. Corner of their garden, on slight slope with good access. Not yet applied for planning, so got long way to go yet. started doing lots of research an reading.
We want a 3 bed eco bungalow, well insulated, triple glazed an with wood burner with back boiler to heat water an radiators. early days, will begin blog an post pics as it moves along.
Lack any real skills, but got great friends an family, intend to sub contract the whole build.
Posted 17 January 2014 - 09:53 PM
Sounds like an interesting project, we've been going through a similar process over the past couple of years, buying a plot, getting planning permission, and designing and building a low energy home.
My advice would be to do some more research before committing to radiators run from a wood stove. My reasonsing is this:
1. A low energy home only needs very little heating - our budget 2 bedroom, 130m2 1 1/2 storey home only needs 1.6kW to heat it to 20 deg C when it's -10 deg outside, the smallest wood burning stove will kick out around 4.5 to 5 kW, massively more heat than the house needs in the coldest weather, so we'd end up opening the windows in mid winter a fair bit of the time.
2. Wood burning stoves emit around 100 times more pollution than a diesel car - eco they are not, not by any form of measure you choose. They are dirty, polluting and use more resources than we have on this small island (to heat a home using wood needs around 4 to 5 acres of sustainable woodland per home, far, far more land then we have available in the UK). Also, wood is very expensive as a fuel, and will get far more expensive as the ratio of consuming wood as fuel increases relative to the limited amount of UK grown wood available. If you have 4 or 5 acres of sustainable woodland to harvest for fuel, then maybe this makes sense, apart from the serious air pollution issues.
3. Radiators are efficient, but they do take up wall space, and limit where you can put furniture. If you only need a small amount of heat input, then have a think about underfloor heating, particularly for a single storey home where you can heat every room this way from a well-insulated slab.
4. Ventilation heat loss will probably exceed insulation heat loss through the fabric of the building. It's a compromise, but look very carefully at airtightness. You really need to massively exceed the very poor building regulations insulation and airtightness requirements, as the cost of doing so in either none-existent or negligible, and the benefits are tremendous. Not only will you have the advantage of lower energy costs, but also lower capital investment in the heating system, so saving on build cost.
Finally, read up on passive house construction. The cost over building conventionally is negligible, the on going energy bills will be tiny (or, in our case, non-existent, despite having all electric heating) and in the long term you'll end up with a higher disposable income, so will have a higher living standard than if you had to pay out higher costs in energy bills.
Our passive house build is coming close to completion. It's built from timber, with local larch cladding, and has just achieved an energy performance certificate rating of 107, which is 7 points above the zero energy requirement at the top of Band A. It hasn't cost any more than a conventional house built to about band C, yet is truly "eco", in that it has a negative carbon footprint and a negative overall annual energy consumption over the year.
I'm not an eco-warrior, by any stretch of the imagination, but it does give me a warm feeling to know that our house not only costs nothing to run, but also absorbs CO2 so contributes, in a tiny way, to cleaning up the atmosphere. I also like the idea of setting an example and leaving behind a legacy that will continue to have little impact on the planet long after I've passed away.
Edited by jsharris, 17 January 2014 - 09:56 PM.
Posted 17 January 2014 - 09:57 PM
Duplicate post deleted :-)
As you'll find, a well insulated and 'Eco' home may well suffer at the hands of a regularly used solid fuel stove. This is largely due to the high amount of heat created with them and the proposed build not requiring any where as much heat to maintain comfortable levels.
Have a read of jsharris' blog and you'll soon see what's achievable and what energy savings can be made with prudent construction methods :-)
Have a read, there's plenty to digest !!!
Posted 17 January 2014 - 10:44 PM
Where to begin to reply... I have read jsharris blog nick, thanks. Its really really useful and informative. It inspired me to introduce myself as I normally never post on these sites.
Start with woodburner and heating
Need 3 small radiators only, or so I thought till I read your replies. Thought combined with mvhr system would be about right? really got heart set on a wood burner, wanted a rayburn but commonsense and budget prevailed. Willing to listen to advice tho, will try to keep an open mind.
Perhaps more details would help, the plot is on side of mountain, in a busy seaside village. The bungalow will not catch sun till 10am. Am 20m from A55 dual carriagway, so noise pollution an issue. Also only 50m from the sea.
We had an informal nod from planning saying plot suitable for a bungalow, an there is plenty of precedent in the area. expecting serious aggro from at least one neighbour, so will tread gently.
We can stay in family home next to plot for the duration of the build and there is no real time pressure.
Will be restricted by height so cant build 2 full stories. Hoping to squeeze 2 beds an toilet in roof space. We want open plan living area, real wood floor. Planned for electric underfloor heating in the bathroom, radiators in bedrooms only.
We have read up on many different building routes, sips, icf, timber etc. We leaning towards blockwork with a rendered finish.
Know not very adventurous, but easier to sell and insure. We intend to live there for minimum of 10 years, but you never know whats round the corner. Thanks again for the replies.
Edited by joiner, 23 January 2014 - 08:41 AM.
Posted 17 January 2014 - 10:52 PM
I like them because I think they look nice and I have plenty of free wood. I don't believe for one minute they are environmentally friendly and certainly not carbon neutral.
Whatever you do, choose one that draws it's combustion air directly ducted in from outside, and choose a small one.
My new build is going to have a rendered finish, but I'm now starting to lean towards an entirely timber building with some from of cement board and then render.
Posted 17 January 2014 - 11:07 PM
You'll need a thermal store to take advantage of the wood burner, if that's the way you'd prefer to go well look at maximising on that.
If you look at fitting much bigger rads then they can run off the store via an UFH manifold at low temp long into the late eve after the fires burnt out. Clever set up will still give you hot water for the morning via use of an economy fed electric immersion maybe. Better than having to get a good fire going before showering/bathing etc but you'd probably benefit greatly from an electric shower simply for 'use ability' and as a back up if no stored hot water was immediately available.
Consider an electric oven and LPG gas hob, you don't want to live like Neanderthals, and the resale would be helped if its a more friendly to all property.
Sounds like a great project, keep the questions coming!
Posted 17 January 2014 - 11:08 PM
Edited by Nickfromwales, 17 January 2014 - 11:09 PM.
Posted 17 January 2014 - 11:23 PM
Nick, was thinkin of thermal store. Thought would work with solar thermal, back boiler, and heat 3 radiators an give plenty of water in summer and winter? With electric top up as needed of course. I had dismissed pv panels immediately thinking solar thermal hot water system would be better an more efficient but jsharris's blog suggested otherwise so now really not sure.
Jsharris, am also a champion of the environment and want to protect it. Keep reading how our energy bills will double or triple in 10 years and want to be a head of the curve when it happens. We want to live a low carbon existence where possible, but dont ask me to give up my filthy diesel guzzling vw camper van or you will see a grown man cry...
Posted 18 January 2014 - 09:26 AM
Edited by joiner, 23 January 2014 - 08:44 AM.
Typo: "summer" for "simmer"
Posted 18 January 2014 - 01:15 PM
What you guys think of these warranties? 3 grand or so just to keep mortgage companies happy? May need to remortgage at some point, so may need one.
Got good friend whose got year's in the building trade to hold my hand for the build. He wants to do my foundations with me, and will get my windows at cost an fit for free. Slowly building up list of recommended trades, and been recommended good local architect.
Next step is to visit one of these home building shows in march for inspiration, then sit down with architect to design house. Then apply for dpp and jump thru their hoops.
Edited by joiner, 23 January 2014 - 08:45 AM.
Posted 18 January 2014 - 01:23 PM
Posted 18 January 2014 - 02:10 PM
Some of the problems we encountered were things like very few contractors having any experience of passive house foundation systems, or building to the high levels of airtightness needed. We also found very few architects (none in our area) who understood how critical to performance some aspects of design were. Our final choice was influenced because we felt that the risk of the whole house performance being far poorer than we wanted if we used separate trades with no understanding of the need to build cold bridge free, with no breaches of the airtight layer all around the house, was just too high if we adopted the approach of using sub-contractors directly. The foundations need to be designed to exactly match the wall structure, so the foundation insulation wraps up and around and joins the wall insulation, similarly the roof insulation has to do the same with the wall insulation. It seemed to me that there was a lack of understanding about things like this, at least amongst some of the builders we spoke with.
When looking at windows don't be fooled by the sales hype. An "A rated" window can be so far off the sort of thermal performance needed for a low energy house as to be pointless. The same goes for triple glazing. It's easy to get a triple glazed glass panel that has a good U value, it's the window frame that is critical to good performance. The figure to look for is the window Uw figure, not the misleading Ug figure many suppliers quote. For example, our budget windows (half the price of the big brand names like Internorm) have a Ug of 0.5 W/m².K, but a Uw of 0.7 W/m².K. I've seen similar triple glazed windows that quote the same Ug figure but don't give the Uw unless pressed - when we pushed one company they admitted that their triple glazed windows had a Uw of 1.3 W/m².K, which is pretty poor and below the sort of performance needed. The same goes for airtightness; will really cheap frames be adequately airtight? Will they have good thermal breaks designed in to the frame?
We have some fairly complex glazing, with a large ~6.5m² front glazed entrance. Despite this we managed to get all our windows and doors (which are passive house rated) supplied and installed for £8,889.25 (zero VAT rated). This works out at about £396/m² for external doors and windows (fitted), with a U value of about 0.7 W/m².K (except for one door that's poorer at 1.2W/m².K), which may be a useful benchmark when you come to looking at costs.
Sometimes, DIY doesn't save as much as you may think, especially if you risk poorer overall thermal performance by doing some work yourself to try and save cash. My guess is that getting the windows we bought on a supply only basis might have saved at most £400, as they were fitted by two blokes in a day. However, those fitting the windows knew how to fit them so that they would remain airtight once installed, and that alone was probably worth the small added cost.
When it comes to PV vs solar thermal it's worth reading the stuff that Ed Davies has written, here: http://www.edavies.m...2012/11/pv-dhw/ . In terms of cost, if you have the roof area then PV is far cheaper than solar thermal for heating the hot water, plus you can get paid for any generated power you don't use, plus PV will always add heat to the hot water, even if the panels are operating at sub-zero temperatures and the tank is already fairly warm.
One thing to watch with any air feed/flue system is the potential for serious air leaks, causing additional ventilation heat loss, and the impact of the flue and appliance on heat loss when it's not burning. In effect, it can act as a poorly insulated refrigerator sat in the room, with the outside of the stove at outside air temperature because of the air flow through the air feed and out the flue. Not only will this cool the house down, but it will act as a condensation focus. The latter is something that needs thinking about - for example, in our build we get condensation on the door locks, because the tiny air leaks through the keyholes make the inside of the door locks cold enough to condense water vapour from the warm house. All four of our door locks do this, and will be dripping wet first thing in the morning after a cold night.
There are a lot of little details like this that need to be thought of when designing and building a low energy home (like not having a letter box that destroys the airtightness, or not setting the electricity meter box into the outside wall where it removes a hunk of wall insulation). With a bit of planning and research they can be prevented and designed out at little or no cost, as long as you catch them before they get built in to the house.
Edited by jsharris, 18 January 2014 - 02:14 PM.
Posted 18 January 2014 - 02:28 PM
wall, not the house...
Posted 18 January 2014 - 04:29 PM
wall, not the house...
Edited by ProDave, 18 January 2014 - 06:40 PM.
Posted 18 January 2014 - 06:36 PM
Was gonna put it well inside my property, an there's a real well established post box meters away.
Posted 18 January 2014 - 07:42 PM
Really struggling to let go of my wood burner, always wanted one an know wife wants one.
Posted 18 January 2014 - 08:00 PM
Posted 18 January 2014 - 08:18 PM
There will be no heating in the pantry and the internal walls will be insulated.
This could be an arguable case for specifying a lower insulation level for the outside wall just where the pantry is?
The latest iteration of my plans has the pantry a bit larger, and the fridge freezer in the pantry.
Now FF's emit heat - from the back.
So the FF will be set into a "baffle wall" so the back 1/4 of the FF will be behind this insulated baffle wall. The void behind the FF will be vented at high and low levels to an adjacent room (possibly with a small fan) to take the heat out of the void space.
So the unanswered question, is will the (relatively speaking) cool front and sides of the FF have the effect of keeping the pantry cool?
I'll let you know when it's built.
I've tried to make our house layout as efficient as possible, i.e as little wasted corridor space as possible. The combined utility and WC is a bit unusual and not to everyones taste, but I can't see anything in building regs to say you can't.
Posted 18 January 2014 - 10:29 PM
Tried to squeeze utility into same space as pantry but couldnt make it work. Squeezed some extra storage into wall below toilet/ utility on your plans, by nicking metre from lounge an dividing it into 3 cupboards with separate access from hallway, toilet an lounge. Your lounge will be our 3rd bed/quiet area.
The more i learn the more I realise how ignorant I am, that seems to stand in most things, my plans an expectations evolve and mutate. Bloody confusing.