tl;dr : For the millions of dwellings that have significant physical constraints imposed by the physical fabric of the building, its configuration and location, that rule out heat pumps, biomass and solar thermal, how can we decarbonise our space and water heating effectively?

The specifics of my home, for context

At the moment there's natural-gas-fuelled central heating, with water-filled pump-driven loop going into wall-mounted radiators that have been sized for an operating temperature of 60-70°C. That's pretty typical for most British homes.

The property is solid-wall construction, and there isn't much external wall - it's mostly glazed. Most rooms are generally tall - about 3m. (a fairly standard late-Victorian British terrace, with some subsequent improvements, including secondary glazing).

It's still quite leaky for air, but we're working on that, and planning to build tight, ventilate right, over time.

We don't have much unshaded south-facing surface. And we're nowhere near any district heating schemes.

There is a garden of about 180m2, with access only through the house. We live cheek-by-jowl with our neighbours, so a heating system of 40dB or more would be too loud. So no heat pumps - the defrost cycle alone is unacceptably noisy, let alone the constant throbbing during normal operation.

Our first emphasis is on reducing space-heating needs through good insulation and air-tightness. But there will remain a big chunk of space-heating requirement, as well as water-heating.

Heating season is roughly October to March, and outside temperatures in deepest winter can get as low as -15°Celsius at times. There may be 30 days a year when the temperature goes below 0°Celsius.

The question

And although our home is unique, it is in many ways representative of millions of homes. So I'm not looking for a unique solution for my own home, but a generic solution or set of solutions for the millions of homes that share the significant features with mine: there are severe fabric constraints that rule out air-source heat pumps, ground-source heat-pumps and solar thermal. Biomass seems an unlikely route, given the local pollution impact of millions of homes with individual biomass burners.

So how can I decarbonise my domestic water and space heating, given the severe fabric constraints?

  • "but a generic solution or set of solutions for the millions of homes that share the significant features with mine" The world's governments would love such a solution; sadly there is none. All retrofit has to be done on a house by house basis (if it's to be done properly and not be at risk from future defect). – Dan Gravell Aug 9 '17 at 10:37
  • Note that biomass is not sustainable at all, the particulate matter is atrocious, worse than a diesel engine and causing 250,000 casualties per year. – gerrit Sep 7 at 17:14
  • A conventional wood stove is a pretty big polluter. There are other kinds of wood stoves, though, some of which use considerably less fuel and produce considerably less pollution (which go pretty well together since most pollution from wood burning is just wasted fuel). – Jean-Paul Calderone Sep 7 at 18:18
  • @EnergyNumbers No acceptable answer in five and a half years? Perhaps it's time to either lock the question or update/re-work it so that it can be answered? – Tim Sep 8 at 6:24

Given that you have natural gas heat I have a hard time imagining that there is a lot you can do there. There are likely some additional constraints given the historical value of the house. I think in many cases it is more important to preserve historical character than to try to fully decarbonize but that's at least partly a personal preference.

Here are some ideas that come to my mind, however.

  1. After focusing on leaky windows and doors, and insulation, what about putting a solar collector array on your roof to help heat the water?

  2. Perhaps you could use this to offset your gas-powered water heater first.

  3. Also if you can, perhaps the capability, and south-facing walls, perhaps passive solar collectors?

Note not all of these may work. None of them may. But they are where I would start looking.

  • +1 - a solar collector would make the biggest and long lasting bang for the buck. – Peter Ivan Feb 13 '13 at 22:39
  • We don't have much unshaded south-facing surface - there isn't any decent solar radiation to be harvested – EnergyNumbers Feb 22 '13 at 18:42

If you have a basement you can install a ground loop. It may not be available in your area, but "remote dive" boring equipment comes small enough now that it can be brought in through your front door. Obviously groundwater and underground utilities are concerns, but it's still possible.

I don't think I'll ever understand people's carbon fixation, but if your electric supplier is selectable surely in the UK there is an renewable electricity supplier, buy only from them, replace the gas boiler with an electric and voila! 99% decarbonized.

Insolation in your locale is probably to low, but if not an evacuated tube solar thermal collector(ETC) will operate in your temperatures to preheat water. ETCs are not uncommon in Alaska and northern Japan where winter temps are even colder.

The glib answer is to use less energy.

The best way of doing that is fixing the fabric of the house - massively increasing insulation, massively decreasing air permeability (and as a result fitting a ventilation system).

There is no technical-wizardry answer. The simplest solution is best (but unfortunately outrageously expensive).

Have it renovated up to Passivhaus standards. This is possible with British terraced housing, For example, see this end-of-terrace house in Lancaster, UK, which from the outside looks like any other leaky British home, but has been renovated up to Passivhaus standards.

In a climate with winters as warm as the UK, there should be no need to actively heat any building.

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