My original idea and goal was to build an autonomous house (or to be more precise — an autonomous homestead) on the property we bought in 2007. But for the last year my wife and I we visited several buildings for sale, and even once or twice wanted to buy the house we saw. Every time I am wondering if it’s better to build your own autonomous house from the scratch, or to build a typical house and to upgrade it and retrofit to the autonomous house standard.
And I am still confused.
In the terms of energy efficiency, it’s much better to build a new house. The buildings we saw for sale this year were mostly built in 1970s, during the time when Poland was a communist country and it was very difficult to get cement, concrete, bricks, windows and roofing materials. Back then people built their houses with what they could get their hands on, and since the coal was very cheap and plentiful, noone cared to insulate walls or install airtight windows. People simply used a lot of energy to keep their houses warm. They didn’t care about getting maximum amount of sunlight for passive solar heating, nor they did care about having efficient ventillation systems.
For example, one house we saw last week, used up to 7 metric tonnes of coal (15,000 lbs of coal) to heat up during entire winter. Since the house is about 120 m² (about 1,300 sq.ft.) large, it used about 320 kWh/m² each year for heating only. This value means nothing if shown without something to compare to, especially if you’re using imperial units. It’s enough to say that very energy efficient passive houses require less than 15 kWh/m²a and typical house built in Poland today requires only about 150 kWh/m²a.
If you build a passive house from scratch (I refer to the passive houses since I believe it’s a wise idea to start with passive house standard and then put some alternative energy sources to get to the autonomous house goal), you can use much better building materials than were used back then. Many of the materials common today (like polyurethane foam, or perlite) were not used simply because noone produced them for the market in Poland. And now you can choose from a variety of different insulation materials (styrofoam, mineral wool, if you’re rich enough you can even use aerogel 😉 ). If you want your house to be as energy efficient as possible, you will set it up so it can gain as much solar energy as possible using large windows on the south wall. And you can get pretty efficient windows. And forced ventilation, with heat recovery. And so on.
When you have a limited budget, you might think that it’ll be cheaper to get an existing house and then to upgrade it later, during five or so years.
It probably won’t.
The house we saw last week had to be totally restored. We would have to add 6 or more inches of styrofoam to the walls, probably more than 8 inches if we wanted to achieve the passive house standards. We would have to demolish the roof and install a new one, that would be insulated, but also because the roof is made of asbestos. We would have to install a modern heating system (right now the house has three or four radiators, all connected to a kitchen stove). We would have to get much better windows. We would have to add a couple of solar air collectors, and a forced ventilation system.
And getting this house would cost us more than building our own. Partly because of the large amount of ground that’s being sold with the house. Probably if we sold our current property we could pay off a large portion of the mortgage we would have to get for this house. Or we could pay for the upgrades…
We’re still thinking whether or not to buy this house and upgrade it to an autonomous homestead, or to build a house on our current property.