We’re looking at windows at the moment, and trying to work out what will fit into our budget while giving us the best possible insulation effect (U-Value). The PassivHaus standards state that our windows should have a U value of <= 0.8 W/m2K, so we’re going to try and get as close to that as possible.

It has been suggested that, rather than going for PassivHaus certified triple-glazed units we should go for double glazing and put up some insulated curtains. I’m not sure that would work for every window we have, but it could deliver real cost  savings if it can deliver a decent U-Value.

Not surprisingly, very few people are prepared to put a U-Value on curtains! But I found this great table over at Action 21. It compares the different U-Values for windows alone, and then the total U-Value if using heavy curtains or insulated  shutters.

Window U-value [W/m2K]
Window only
(daytime / nighttime)
with heavy curtains
with insulated shutters (nighttime)
Single glazed 4.5 3.3-3.6 2.6-3.1
Double glazed, 12mm cavity 2.8 1.9-2.3 1.3-1.7
Double glazed, 16mm cavity, low-E 2.0 1.2-1.6 0.7-1.1
Triple glazed 2.5 1.7-2.1 1.0-1.4
Triple glazed, 2 low-E, Argon filled 1.7 0.8-1.3 0.4-0.8

So it looks like we could get down to 1.2-1.6  with curtains – it’s not 0.8, but it’s pretty close, and according to this table is lower than standard triple glazing.

So this is well worth consideration – but what type of curtains would we need to get those results? Here’s what the Yellow House have to say:

Ecodesign books sometimes talk of “insulating curtains”. These would have to be home-made curtains of insulation sewn between fabric. In order to avoid downdraughts from the window they must fit snugly into a pelmet at the top and a tuckslot at the bottom. In theory an insulating curtain with 60mm mineral wool reduces the u-value of a double glazed window by 75% to 0.6. However they very hard to clean, and there are potential health issues with sharing a living space with mineral wool. A better option might be to convert old duvets into curtains, or make insulation shutters from timber and insulation sheeting. Our feeling is that all these options represent a major intrusion into the living space and are not appropriate for a normal house – though they would be justified in a solar house where there are very large areas of glazing.

Duvets at Sainsbury’s are now incredibly cheap – so maybe that’s what we’ll go for – I’ll chase up prices against triple-glazing.


I’d been planning to put together a list of aims and achievements since I talked about it back in August. In the great pause between Christmas and New Year it seems appropriate to finally get around to it! So here is my quick brain dump. I’ll expand on this as I achieve some of them:


  • Build up a store of 1 year’s supply of food that we eat. Try to ensure that we are storing the ingredients for food that won’t keep – e.g. store UHT milk to make short-shelf-life dairy products as required, ingredients for bread etc.
    • Work out what we eat in a year
    • DONE! learn to bake bread from base ingredients
    • learn to bake good, light, everyday bread!
    • learn to make basic pastas
    • learn to make and wax hard cheese – cheddar, parmesan and more
    • learn to make soft cheeses that we use – feta (soft and hard), mozzarella,
    • learn to make other dairy products that we use – sour cream, yoghurt
    • learn to preserve and store fresh food that we grow, or that is only seasonally available locally.
    • learn to make jam
  • Find a network of  local producers and suppliers, and use them as much as possible.
    • reduce our dependance on supermarkets to less than 50% of essential food
      • reduce our dependance on supermarkets to less than 10% of essential food
    • reduce our dependance on non-local food – less than 50% of essential food
      • reduce our dependance on non-local food – less than 10% of essential food
        • remove our dependance on non-local food – no essential food from further away than 100 miles, 90% within 50 miles


  • get milk (and juice if possible) delivered in reusable bottles
  • shop for a month with no plastic bags
  • compost all kitchen scraps, so that all waste from the house is “dry” and doesn’t need plastic bags
  • halve the packaging we use in year 1
    • reduce it by 10% every year
  • Halve our general refuse in year 1
    • reduce it by 10% every year thereafter
  • put in a compost toilet
  • put in a greywater recycling sytem for all water from bath, shower, washbasin, washing machine

Growing our own food

  • setup our aquaponics system
    • harvest fish from our aquaponics system
      • breed our own fish, thereby closing the cycle
  • harvest winter vegetables from our own plot
  • get an allotment
  • grow 50% of our own fruit and vegetable requirements
    • grow 80% of our own essential fruit and vegetables
  • keep chickens for eggs


  • work out how much electricity we use, and try to devise a plan to provide that by renewable means
  • reduce our fossil fuel use by 10% a year
  • store at least a year’s supply of firewood
  • have a heating/hot water system that will work with at least two different fuel sources
  • have a cooking system that will work with at least two different fuel sources
  • don’t buy or use a tumble dryer
  • retire our powered mower
  • provide all our essential power needs on-site, for at least a month
  • provide 50% of non-essential power needs on site

General Resilience

  • provide 100% of essential water requirements on-site for 3 months
  • provide 50% of all water requirements for 3 months.
  • “live” within a bikeable radius (public transport if necessary)
  • learn to sharpen tools


  • Join local allotment / gardening groups
  • Get involved in Manchester FOE
  • Go to Green Drinks
  • Team up with other local growers to ensure that we can have some “cover” if we ever go on holiday.

The learned folks over at the Association for the Study of Peak Oil and Gas have published a really clear, well thought-out Guide to Peak Oil by Chris Nelder. This differs from a lot of Peak-Oil stuff I’ve seen, in that it doesn’t immediately suggest arming yourself and heading for the hills. It takes a powerful message and delivers it in a calm here-are-the-facts way. Here are some of the highlights for me:

  • We are not about to run out of oil – it’l be around for a hundred years.
  • We seem to be entering a plateau in oil production, and oil production is unlikely to significantly increase from this point.
  • Following the plateau – within 3-6 years – less oil and gas will be available to feed, clothe, transport and support an increasing – and increasingly wealthy – world population.
  • New sources of “oil” – Tar Sands, Shale Oil etc. require significant energy to convert them into a relatively slow supply of usable liquid fuels. This means that they are not likely to reduce the current oil prices, and will only be economical at significantly higher prices, if at all.
  • Within 10 years we can expect to be living with 12% less oil-per-day than we currently enjoy.
  • 11 of the top 21 oil producing countries are already past their peak, and production from mature oilfields declines at around 4.5% a year. Any new discoveries have to offset this loss before they give a net increase in oil production.
  • Event the International Energy Agency, who are on the more optimistic side of energy forecasting, have dropped their forecast growth in supply, while acknowledging that demand for oil continues to grow at 1.5% a year.

It’s pretty sobering reading, albeit nothing I wasn’t already concerned about. If you’re just starting to think about peak oil, and it’s effect on you, your children and and your community then this document is a good place to learn the basics – read it and pass it on to anyone who might have an interest in the future.