Our Budget Eco Bungalow
Posted 18 January 2014 - 11:05 PM
Posted 19 January 2014 - 08:55 AM
Found a list of 7 principles of design.
Work with the sun, orientation and correctly positioned windows.
Thermal mass, to absorb an retain heat
Stack effect, controlled drafts
Thermal zoning, heating whats needed when needed.
Embodied energy, local materials and trades where possible.
Energy conservation, insulation, triple glazed etc. Want lots of led lights
Live like granny, this my favourite one. A simple frugal existence, with no wastage. we make wine, chutneys, jams etc. Can mill own wheat an bake own bread. (When tescos shut)
Found these principles early in my self build process, an seems to echo lot of what I read here.
Posted 19 January 2014 - 09:21 AM
In your case you can combine the first point, about orientation with the sun, with your need to keep out the noise of the road to the North West of you. If you avoid windows in the North elevation you'll cut down on the noise getting in to the house.
Thermal mass is a mixed blessing in a very low energy house, of far more importance is the decrement delay of the insulation system you choose. For example, if you have a high thermal mass (which is really a misnomer, as what is meant is having an internal structure that has a high specific heat) and a low decrement delay insulation, then this can result in high overnight summer temperatures. What happens is that the low decrement delay insulation allows the high specific heat interior to warm up late in the day in summer. This heat is then released back into the house during the evening and night, which can mean that you have higher overnight summer temperatures than might be comfortable.
My own view is that you are better to look at having an interior with a relatively low specific heat, so that it has a fairly rapid response to heating/cooling, and then using an external insulation system that has a high decrement delay. The high decrement delay will limit the amount of heat that gets into the house at the end of a long hot summers day, and will also allow more rapid cooling from ventilation in the evening as the outside air temperature drops. Similarly, the house will respond more rapidly to heat input, with zones heating up far more quickly (if you opt for a zoned system). If you build in a high specific heat internal structure, then zoning becomes of limited value, as the response time of each zone may be too slow to make it worth trying to change temperatures in order to best suit your pattern of living.
When looking at glazing that is facing south to south west, be conscious of the potential for overheating the house in summer. There are several ways to ensure you get good solar gain from winter sunshine, and yet restrict the solar gain in summer. One way is to put south facing windows under some form of overhang, like a brise soleil or extended roof. This relies on the angle of the sun being higher in the sky in summer, so the overhang provides shade over the window then, but still allows lower angle winter sunshine in to warm the house. Other ways are to use external shutters or blinds to restrict summer overheating, but these need positive intervention in order to stop overheating (which can be useful, as it gives a degree of control).
When it comes to LED lights there is a great deal of variation in light output, colour and efficiency. There's also a question mark over the reliability of 240V LEDs. We're using a lot of 12V LEDs, but I did test a lot of different types and found massive variations in light output and efficiency. Even the very best LEDs I found were barely more efficient that CFLs and the majority I looked at were less efficient than CFLs, so weren't the best choice in terms of the lowest energy way of lighting a house.
It's hard to make use of natural ventilation in a house that is inherently airtight. There are passive heat recovery ventilation systems available, that use stack effect, but they are very expensive and there are question marks as to the efficiency of their heat exchangers. If it were me, then I'd look at this as purely a means of enhancing night purge cooling through open windows in summer, if you need it.
Edited by jsharris, 19 January 2014 - 09:23 AM.
Posted 19 January 2014 - 10:08 AM
12v leds are what im after, jsharris. Got experience in them from my campervan. We also have lots of leisure batteries and inverters lying around as family also have caravans an campers. Had a notion to build in an12v system to charge all our usb devices directly into the house. Have seen few electric twin sockets with usb ports built in. Thought could run 12v leds from batteries if we have powercuts. Probably bit of overkill... Seal designs do good range of leds, got them in my camper
As to natural ventilaion, an stack effect. Yes I also took that to mean open a window when it gets hot...
have planned small windows in most of front, but need big one in kitchen to claim sea views. its always a balancing act.
Thanks for your feedback.
Posted 22 January 2014 - 11:03 PM
Still pondering on the woodburner, trying to let it go but struggling.
MVHR systems? I believe some of them have built in heaters that can give a boost when needed. Are they any good?
Posted 23 January 2014 - 07:40 AM
As an example, our house exceeds the PassivHaus standards for airtightness and insulation level and we could *just* get away with providing some of the heating via the MVHR. In theory the MVHR we have can add around 2 kW of heat to the supply air feed, but to do that the fans would have to be at boost, rather than the normal trickle level. As a way of relatively quickly heating the air in the house up from cold (say when returning from a winter holiday) it may be OK, as it would warm all the air in the house in about 1 1/2 hours, which is probably quicker than waiting for the slab to heat back up with the low power UFH. Where the ability to add heat to the MVHR fresh air feed has a more realistic benefit is when you want to totally eliminate the slight temperature difference between the air in the room and the slightly cooler fresh air from the MVHR (MVHR is around 85% efficient, so although the outside air coming in is heated by the heat exchanger is doesn't quite get to room temperature). Most people find this isn't really needed, but it could be useful if your layout forces you to have fresh air outlets close to where you might be sitting or sleeping.
Posted 23 January 2014 - 08:50 AM
Posted 23 January 2014 - 12:09 PM
Posted 23 January 2014 - 12:25 PM
Allowing for solar heat an the airtightness an super high levels of insulation and myhr system, if I skip woodburner and gas central heating, will I still be toasty an warm? House will be very exposed, struggling to believe it can really be hot enough for us. Forgive lack of faith...
Posted 23 January 2014 - 01:10 PM
Can't say I'd recommend the slab idea, especially with the air bricks!
Posted 23 January 2014 - 01:19 PM
Posted 23 January 2014 - 04:13 PM
Edited by rickwales, 23 January 2014 - 04:28 PM.
Posted 23 January 2014 - 04:21 PM
This allows the cooker hood to remove the grease before the MVHR gets to extract the air from the kitchen.
Posted 23 January 2014 - 04:57 PM
Back up electric panel heaters can be anything you like, they only need to be low power and have a thermostat. There a lot's of makes around, I'm planning on fitting something like this: http://www.tlc-direc...s/DXPLX500.html if I really have to, but strongly suspect that they won't be needed at all.
The MVHR should have a summer bypass, allowing it to pump outside air around the house directly in summer, so providing the means to cool the house a bit. Designing the house so that you can cross-ventilate by opening windows on opposite sides helps a lot as well.
The advice above about the cooker hood is spot on. Use a recirculating one with a grease filter and let the MVHR take care of extraction. The MVHR should extract warm, humid or smelly air from the kitchen, bathroom, WC and utility room and pump fersh warmed air into the living rooms and bedrooms. This means that the air flow direction in the house will always be towards the kitchen, bathrooms etc, helping to control the spread of smells and humidity around the house, as well as recovering heat and reducing ventilation heat loss.
Posted 23 January 2014 - 05:34 PM
Spent time scanning viking houses website and another popular green forum today, beginning to realise it wont be easy to achieve the levels of insulation and airtightness I want an need to achieve with block an mortar construction even with the thin joint system I'd heard about.
Posted 23 January 2014 - 05:40 PM
Posted 23 January 2014 - 05:44 PM
The best option if looking at using block construction is probably to use an insulated raft foundation with a wrap around upstand (like the Isoquick, Viking Passive slab or Supergrund systems), then build a single skin block wall and fit external wall insulation. Inside you can either use a very carefully applied cement render parge coat under the plaster to get the airtightness you need, or opt to fit an airtight/vapour check membrane and then dryline off battens, giving a service space.
Posted 23 January 2014 - 05:54 PM
Really liking the viking slab, looks simple an very efficient. can we install it ourselves? Can it be laid on clay?
Not that im a bear grills fan, but i remember one episode where he said one layer below was worth 2 above when sleeping on the ground. must be same for houses.
Posted 23 January 2014 - 06:05 PM
Yes it can be laid of clay (ours is) but it depends on the type of clay and whether or not it's susceptible to heave (ours isn't, it's hard gault and doesn't move at all between wet and dry). If you're on soft clay that's quite deep, then you may need a thicker layer of crushed stone underneath. If your ground conditions are really poor then you may even need piles and some form of supporting structure. It all comes down to the exact soil type under the area where you want to build.
The "one layer below is worth two on top" doesn't really apply to houses. The ground temperature under a house will be a fairly stable 7 to 8 deg or so all year around, and heat loss is proportional to the temperature difference across the insulation. If the house is at 20 deg C inside and the air outside is at 0 deg C, then the heat loss above will be driven by a 20 deg C temperature differential, whereas the heat loss down to the ground will only be driven by a 12 deg temperature differential. This means that in general you don't need any more insulation underneath than in the walls.
Edited by jsharris, 23 January 2014 - 06:08 PM.
Posted 23 January 2014 - 06:39 PM
Coming round to timberclading tho, seen some beautiful examples.
I have to build on a budget, but if I didnt im sure with help I could (with lots of help) design an build the house of our dreams. There are so many lovely lovely things an I want them all. My challenge is to try an incorporate as many of mine an my wifes dreams as possible into a 9 by 12 building.
Thanks again, rick