This is Part 1 of a series of articles and diary of building the green dream, but first the ‘gold standard’ the German ‘Passivhauses’.
Passivhauses is certified standard of house building that can increase the value of your home, reduce insurance but principally reduce heating to the body warmth of the occupants and appliances. Cooking and hot water are the only big energy consumers with an air heat exchanger [costing around £20-£40 in electricity per year] conditioning the hot air from your bathroom, kitchen and other humid areas and exchanging its heat with clean cool air from outside. The Guardian article on how Passivhauses have changed peoples lives and heating bills has a simple diagram of the principals. It also stimulated plenty of comments of people living in Britain’s energy inefficient houses on how to retrofit the Passivhauses features into theirs.
The cost difference between a standard UK new build [with a build cost of £80,000] and a fully spec Passivhauses is £20,000- that may seem a lot [or little, and the coming blogs will investigate how much it costs to build a house] but given that UK energy prices have doubled since 2005 the savings are potentially huge.
Why don’t people get exponential growth? I wrote about it and it seems obvious now but not before. Fuel or at least good old fashioned fossil fuels are never going to be cheap again [unless we have a major economic collapse and demand crashes but then we won’t have the income to buy it], the alternatives like nuclear isn’t getting cheaper and wind and solar may, but not quite yet [although not to be dismissed]. The latest wave of price increases by the Big 6 UK energy providers is around 10%, it is exceptional but with income only rising at 1% and general inflation at 2.5-3% even modest above inflation energy prices rises has long term implications.
The average UK household energy bill is £1400, but like so many ‘averages’ it hides the reality that poorer households in poor property are spending a higher percentage of income on keeping warm and possibly more than the average middle income family in a better insulated house with the best gas boiler. With a 7% annual energy inflation the average fuel cost will double in 10 years, and double again 10 years later. 7% inflation may be the high end, it may also be a low guess given that we have used up half the oil resources in the world and will consume the rest in decades and global population increase is demanding more energy. Assuming a 7% inflation [and only 1% increase in real income] means that over a 20 year period the average household will spend in the region of £60,000 to keep warm, have hot water and cook.
There is an old axiom that rich people buy once and save money [I can’t remember the actual saying] poor people buy 10 pairs of shoes whilst the wealthy buy a good pair that last. Spending money now to save later is not always possible especially on a low income but it makes sense if you can to reduce energy consumption [and CO2] to do so. As a builder and eco-enthusiast I have been consulted on energy efficiency retro fitting as well as doing the tasks, and as I’m currently embarking on building the green dream [see the next blog when I download pictures on the current project] energy efficiency is a priority.
Recently I did the research and plans to renovate a 18th century town house to very high energy efficiency standards. A problem with it was that it is Grade 2 listed which requires a jobsworthy inspector overseeing renovation work to ensure the building’s character is preserved. Unfortunately pretty well everything suggested was considered to be almost vandalism and as a consequence the building remains on the market and unrenovated. It was was an interesting exercise in costing and planning a major retrofit.
Renovating and retrofitting compliment each other- if the roof needs removing and repairing then it is an excellent opportunity to fully insulate at little additional cost. Likewise is the ground floor needs lifting [the house had slate slabs that were damp and laid on to soil] then a new concrete slab can be laid with suitable insulation and then the original floor can be replaced again at minimal additional cost. However a problem in the UK is that builders are not familiar with efficiency measures and will skimp on material costs to keep their quote competitive. Knowledge is power and the homeowner needs to up their understanding of the options, a daunting task given the confusion over U values, R values, and Watts per square metre.
The principle is simple-
have an insulation barrier of 1 foot [270-300mm] of most materials [glassfibre, recycled paper, thermal blocks etc] or half as much of polyurethane envelop the entire building. Ensure there are no leaks – which requires wrapping the building [usually internally] in an air tight membrane before plaster board is installed- and making sure any punctures in the building such as pipes are sealed. Have draft free doors and windows and control the ventilation with a heat exchanger.
the practise is tricker.
The best advise is to DIY, or at the least fit your own loft insulation- glass fibre is cheap and laying another roll in the roof space will do no harm, particularly pay attention to the hard to reach eaves: drafts that come up around floor boards have there origins at the point the wall meets the roof.
If you are up for a challenge learn to plaster [and be able to remove skirting boards]. External walls can be insulated by removing skirting, window trim [pictures etc] – gluing either 100-150 of PU foam board or twice as much polystyrene sheets on to the walls, then gluing [there is a plasterboard sticky plaster for the job] plasterboard on top and then finishing the board with plaster. You can glue the skirting back on but it serves no purpose. To really do a good job, insulation [glass fibre] needs to be placed in the void between ceiling and floor along the external wall. The rooms will be smaller but much warmer- and you can do one room[ one wall] at a time.
A DIY project that is cheap[er] and effective is to insulate the ground floor. If it is a floating timber floor the boards can be lifted and insulation stuffed inbetween the joists- either staple fruit netting to the underneath of the joists and fill with glass fibre or use PU foam rigid boards. Whilst you are down there use PU foam in a can to seal any cracks in the walls. Buy the foam gun rather than the cans with their own applicator- they can also be used to fill gaps around pipes in external walls.
Concrete floors are more of a challenge- you could get a breaker, dig up the floor to a depth of foot, lay membrane- 6inches [150mm] of polystyrene, or 75-100 mm of PU foam board, include 50 mm upstand along external wall to avoid cold bridging, and replace the 125mm of concrete. If all of that sounds like a lot of trouble then laying 50 mm of foam board directly on the floor and then laying floor boards on top is the alternative. You will have to cut the doors down, remove the skirting and hope the electrical sockets are not too close to the floor.
Double glazing is pretty ubiquitous in most UK homes even old ones, as long as they are sound there is little economic reason to replace them. If they are up for replacement then it is questionable if triple glazing is worth the energy savings. A passive house- rather than a Passivhauses utilises the sun rays [in winter months] to enter the house through south facing windows and heat the interior- by installing triple glazing that heat is deflected to a degree so in latitudes of 50o it is questionable to install triple glazing in south facing windows. What I would recommend is removing the plastic trim around double glazed windows [it is stuck on with silicone that can be cut with a knife] and in the void between the walls and frame fill with expanding PU foam. when cured trim and replace the plastic strips with white silicone.
If you have been really diligent in insulating and draft proofing your house you will find mould growing everywhere. Bulk ventilation removes warm air which contains more water from breathing, boiling the kettle and having a shower- reduce the ventilation [or draft] and the water will condense and provide a home for mould. Even in a poorly insulated house the benefits of an air heat exchange unit have been proven in studies. A number of housing associations have done basic draft proofing, replaced the boiler for a new condensing gas boiler and installed heat exchangers- 70% of heat is recovered [less the moist air] and returned to living spaces. The biggest problem was changing peoples habits- windows need to remain closed- but not during warm periods- and the machine needs to remain on- and not switched off at night. In summer they are switched to a non heating mode and running costs are £20- £40 a year. With a fan[s] being the only moving part there is little to go wrong.
At around £700- £1000 the heat exchange unit is a simple machine that is easy to fit- the ducting is more problematic but if you like the industrial look it can be on show- I would chose galvanised duct. Otherwise it has to be installed through walls and between floors. Kitchen and bathroom extractors are removed and replaced with input ducts- you would also want to have a means to seal chimneys- at least whilst they weren’t used. You also have to install carbon monoxide detectors- by law. They’re cheap so buy 2 or 3. If £1000 is too much to out lay in one go there are individual room heat exchangers that require a hole in the wall and cost around £300.
Personally, I have rented old leaky houses that were almost impossible to keep warm and that was when energy was pretty cheap. One of the simplest tricks was to open up the old fireplace and fuel it with skip diving activities. In the heady days of the 1980s and 90s the skips of towns and cities were brimming with furniture, parquet flooring, and builders timber- either furnishings, renovation material or fuel for humble rented accommodation. Living should be comfortable and a reason beyond saving money and reducing CO2- we mortgage our lives to live in a better [as in a pleasing] house, in a better environment, in a better neighbourhood and comfort including air quality shouldn’t be an afterthought. Smug and snug.
Next Part 2- building the dream in the land of rainbows.