I’ve been looking at options for sustainable housing recently following a raft of competitions for housing associations who want to achieve Level 5 of the Code for Sustainable Homes. Level 5 requires zero carbon emissions from heating lighting and ventilation, so you have 2 options; install a conventional boiler and enough extra PV to offset the carbon or install a biofuel boiler. Since PV is vastly expensive, this really only leaves the biofuel boiler.
Now, we can design well insulated housing these days with peak heating loads well below 5kW. However, can you find a fully automatic woodfuel boiler below about 15kW in output? No – at these low loads the only option seems to be manually fuelled room heaters. Wood boilers really need to be fired at full power for a reasonable period to avoid problems with tarring up. In other words the smallest automatic boiler is sufficient for 3-4 homes at CSH Level 5 or 6. This is great if you are a housing association and can install common plant and distribution, but what about developing housing for private sale, or even single properties.
The Government insists that all new housing shall be CSH Level 6 by 2016. So, if you are building a single house and don’t fancy inconvenient manual fuelling, you’d be better off not insulating the house at all in order to create sufficient load for long term reliable operation of your woodfuel boiler After all, the fuel is carbon neutral so you get all the credit even if your consumption is excessive. How stupid is that?
I think that this is another example of legislators adopting a voluntary code and forcing it on the market without ever considering the implications.