RenewableCandy wrote:In any case, why value things in terms of their "pay back".
A very good question in general, but we're talking about a system here that relies, for its running, on installations paying back their costs, so that the costs can be paid using the price of the energy saved.
I would argue that we're dealing with a system of consumption; and just as is the case that some people drive an old Ford whilst other people drive new Audis or BMWs, so some people "consume" solar PV or wind turbines for reasons other than the pay back (and in reality, I see an awful lot of houses with big PV arrays which also have an Audi or BMW in the driveway
).
The real issue here is not pay back, its the long-term viability and resilience of our choices today -- and in a climate where such longer-term options are not on the agenda, perhaps because they philosophically negate the whole "conspicuous consumption" paradigm, the "pay back" measure is leading people to make some seriously dodgy choices. E.g., if we move to a situation where power cuts become more common (which is the norm for the majority of those with electricity supplies in the developing world) will the adoption of micro-generation be purely an issue of pay back?; and if grid reliability falls, will people be buying the gadgetised grid-synchronous systems that are the norm today or will they prefer a battery-backed-up grid independent system?
On that note...
DominicJ wrote:Its not the same as a car. Because a car is a recreational spend as much as a practical one.
And the level of, or source of home heating is not?
I don't drive, and that's always been a conscious choice on my part (hence no driving licence). In terms of my work that's brilliant because people pay my travel expenses. How do you assess the "pay back" of that decision?
You can't, because that's a lifestyle change that can't readily be reduced to a common measurement. E.g. how would you put a monetary value on my hatred of insular metal boxes?
Likewise, when we're looking at the difference between solar thermal/PV or gas, or installing heat recovery rather than having a leaky house, whilst we can create a more readily apparent common measure, it still can encompass the varied reasons why we might adopt certain issues.
The most basic feature of any "pay back" calculation is the assumption of stasis -- the idea that the conditions or our values today will be the same in the future. But more importantly "pay back" has become the justification for change for many of the campaign groups and policy wonks who want to market an ecological view of the world which is devoid of any critical content; it's a faux version of change which represents no significant change at all, and therefore doesn't address the root causes of the reasons why people carry it out. In reality, and considering the likely changes in the supply capacity and stability of our energy systems, stasis is the last thing that you should assume when making a choice on what to buy today.
E.g., air-source heat recovery systems are very nice pieces of kit, and can cut energy consumption significantly which gives them a fairly good payback; but they're also extremely complex systems that require a number of specialised parts to function. Therefore, in the event of technical complexity unravelling, they're more risky than, for example, a micro-hydro or micro-wind option which are more easily maintained/rebuilt using basic engineering skills and tools. However, the price of failure for a house with heat recovery is higher still, compared to other options, because of the very high leak proofing these systems require to function effectively -- if the system fails and can't be fixed, or you can't get enough power to make it function, the air quality of the house will quickly fall and after a prolonged period will reduce the liveability of the house.
So, how do you reduce the complexity of that issue to the simplified common valuation of a "pay back period"? That ultimately is the flaw in pay back as a value in decision making.
DominicJ wrote:I believe kens arguement is to add a third layer to my double brick build, outside.
Battoning and clapboarding the outside of a house, especially one without a cavity, makes a significant difference to heat loss; and if you've got a porous brick/stone and lime mortar envelope it can make a big difference to damp/rain infiltration too (I wanted to do it here, but was told no because this is a "conservation area").
Even though wooden cladding a very effective and relatively low impact option compared to rebuilding with dry lining, planners don't like it because it "looks different". And I bet that the new "presumption in favour of sustainable development" doesn't change that outcome either!