When I first took Passive House training and looked at the PHPP I could tell what most of it was… until I got to the District Heat page. The term was not one I was used to. Google to the rescue and I had my answer – a way to provide heat to a large district, area, or region by means of hot water or steam piped through insulated underground pipes.
To someone who has spent most of her life either in a rural house or apartment that had its own dedicated heating source the concept seemed almost Victorian. Radiators? Are you kidding me? Over a big distance? Archaic! Wasteful! Oh the insolence of us rural Americans at times, eh? Assuming we must have the best system because whatever system we have surely must be the best! As it turns out District Heat is actually quite an efficient and low carbon production heating source.
When I talk about over a big distance it really hit home how big a distance some of these systems must cover when I saw this picture of district heating pipes going under the Rhine river. If I didn’t know better I might assume that these pipes were oil or gas for heating, perhaps water for drinking. It would never occur to me that they could be insulated pipes transferring heat at great distances.
I admit freely that I am not a know-it-all (even on the internet) and am thrilled to learn something new. I know that old buildings in large cities would use boilers for radiant heat within their buildings, but the concept that broadening the area to several blocks or an entire city puts things in a new perspective. Some of the facilities, called cogeneration facilities, generate power and heat.
Once you start thinking like that then you realize that perhaps there are new ways to consider community development. While we are busy figuring out that people need mass transit within a half mile walk, that food deserts where there are no grocery stores over a vast distance are a bad thing, or painting roofs white to limit increasing heat islands in large cities, perhaps we should think of ways to plan a common heat provision. Some areas have great geothermal potential naturally and those would be ideal without adding the burning of fossil fuels to heat the water. I just read of a commercial district heating project near Bend, Oregon that got the go ahead to try creating steam by pumping water into volcanically heated rock.
There are other water heating methods and burning community waste might be an option over burying it in a landfill. Someone needs to crunch the numbers, but surely it might be time to rethink the mega furnace in every home approach while we are planning for the future.
If you are using a District Heating method for your project, the PHPP will need to know what kind it is - geothermal, or fossil fuel based, and what kind of fossil fuel as well as how much of the resultant energy is used for heating verses power. Solar thermal space heat systems are not automatically modeled and will need to be calculated and entered manually.
District Heating is Regional Heating is Global Warming – but the good kind!
Next up the Boiler worksheet.