I am stirred to write by some correspondence I have been having with Nick Grant, a water maven and a leading light in the AECB. Nick has recently come out against rainwater harvesting (RWH). He now reckons it’s a complete waste of time and energy and lists no less than eight reasons why you should avoid it. These being:
1. Very cost ineffective — about £15/m3 life cost for RWH assuming pump doesn't fail after 2 years. (By way of comparison, mains water costs around £2/m3.)
2. Doesn't save enough water to be meaningful, and can't be installed in enough places.
3. Doesn't work where needed. Thames gateway — no roof area/person, nor rainfall, even less in a dry year when needed to save water.
4. Can fail, leading to mains top-up running to waste and so undoing all the savings that could ever have been made.
5. Problems flushing loos when power off or pump broken
6. Uses 2-4 times the energy of mains, but still only a little compared with water heating. However that debunks the idea that all houses should have RWH to save all the CO2 needed for pumping mains.
7. “Ah but what about all the chemicals and other environmental impacts.” Again, argument needs to be that rain is significantly better than mains to justify the green premium, but is actually worse.
8. “Ah but I want to save water, but don't want a low flow shower” (perhaps meet CSH 3).
He is not alone. There is a considerable weight of opinion gathering to dis rainwater harvesting as a green con. I am not so sure, but then I don’t know that much about it. But it strikes me that there is now a fairly long list of supposedly eco-products out there that have been slated for being worthless. I can think of:
• multifoil insulation
• polyurethane foam insulation sprayed under roofs
• micro wind turbines
• electric heat pumps
• green electricity tariffs
• magic energy savings devices (as made by EPS who have a very strange website indeed
• green roofs
And then there are products which some people advocate, whilst others think are a complete waste of time. Think maybe limecrete. Or hemp. Or biomass boilers. Or micro-CHP. Or perhaps triple glazing. Or even mechanical ventilation with heat recovery.
I have no doubt that people making and selling these products don’t start out to con anyone but that, quite naturally, they sell their good points and ignore the bad ones. Any visitor to Ecobuild can’t have failed to notice that every single exhibitor trumpeted their green credentials — and why not? But logically, some products must be greener than others. Thus far any attempts at producing an authoritative overview — such as the BRE’s Green Guide — just produce howls of protest from people who don’t like what they see there.
It makes it all very hard for the consumer to make sensible choices. And I can’t see it getting any better, as more and more green products arrive in the market place and there are no agreed systems for testing their claims. Seeing as the government has been offering grants for some of these dubious products, and including others in its Code for Sustainable Homes, what hope is there for us mere mortals to make sense of any of it?