Articles published in 2010
Ground Source Heat Pumps
Exhaust Air Heat Pumps
Last month, we looked at heat pumps which extract their heat from the ambient air outside the house – Air Source Heat Pumps. Another source of heat may possibly be exhaust air being expelled from a house by a mechanical ventilation system. Heat can be extracted from this by an Exhaust Air Heat Pump (EAHP). The amount of heat available is small, limited by the amount of stale air that is to be expelled. However, it may be more than sufficient for heating the Domestic Hot Water. It may even be enough to contribute significantly to the space heating of an ultra insulated and airtight home.
Heat Pump Miscellany
Over the last few months, we’ve looked in detail at the different types of heat pump available – taking their heat from the ground, outside air, exhaust air, or water. To conclude this series, here are a few miscellaneous aspects of heat pump systems.
Feed In Tariffs
A government target is that 15% of all energy used in the UK will be from renewables by 2020. And the government’s intent is that by that date 30% of our electricity will be from renewables. Towards this end, the Renewables Obligation was introduced in 2002 to coerce electricity suppliers to obtain more electricity from renewable sources. As a result, the generation of renewable electricity has increased from 2% in 2002 to 6% now – but that still leaves the UK near the bottom of the European league table.
Sustainable Energy I
Over the last few years, many of my articles have been about the different ways of reducing carbon emissions from houses. To this end, the first priority is to reduce the need for energy by reducing heat losses... A good way to find guidance ... , and to get a grasp of the bigger energy picture, is to read David MacKay’s 'Sustainable Energy – without the hot air'. This important and entertaining book is more than 360 pages long, and there are fascinating nuggets of information scattered throughout.
Sustainable Energy III
In the last couple of articles I’ve been summarizing the excellent book by David MacKay, Sustainable Energy – without the hot air. We’ve seen how the Cambridge professor has estimated that in the course of an average day a typical, affluent Briton requires, directly or indirectly, about 195 kWh of energy in order to to sustain his/her lifestyle. And we’ve seen how the professor has estimated that, when only the physical constraints are considered, the UK could produce almost that amount of energy from its renewable resources – about 175 kWh of renewable energy per day could theoretically be generated for each person, mostly from the wind, the sun, and the tides. But when it comes to real life, and the financial, social and environmental constraints are also considered, MacKay reckons we can realistically expect to get only a tenth of that figure – about 18 kWh of renewable energy per day per person.
So when we stop dumping our waste CO2 (carbon dioxide) into the atmosphere, there might be a huge energy deficit. How would we manage?
Air Source Heat Pumps
Heat Pumps - Other Sources of Heat
In the past few months, we’ve looked at Ground Source Heat Pumps (GSHP’s, popular with UK selfbuilders), Air Source Heat Pumps (ASHP’s, popular with the commercial sector), and Exhaust Air Heat Pumps (so far little used in the UK, but popular in Sweden, for example). There is another possible source of heat, an excellent source for a fortunate few: water. Only a few sites offer the opportunity, but when suitable water is available, a water source heat pump can be very effective.
Two Shows
A sign of Spring is the National Homebuilding & Renovating show, held in March at the NEC – I’ve been to every one of these shows. What was new for me this year was a visit a couple of weeks earlier to Ecobuild, at Earls Court, London. I’d heard good reports about the show, and decided it was time to see it for myself.
The Renewable Heat Incentive
Last month we looked at the Feed-In Tariff scheme, by which a householder is paid for producing electricity from renewable sources. There is intended to be a somewhat similar scheme for rewarding householders who produce heat from renewable sources: the Renewable Heat Incentive (RHI). The FIT scheme was implemented in April of this year; the RHI is due to be implemented in April of next year. However, if you install heating equipment before next April, whether in a selfbuild or not, you should make yourself familiar with the details proposed for the RHI: the scheme is to be applied retrospectively to renewable heating equipment installed after July 15, 2009 (when the Renewable Energy Strategy was published). Note in particular that the installer and equipment must be MCS certified.
Sustainable Energy II
Last month I began my loose summary of David MacKay’s excellent book, Sustainable Energy – without the hot air. We saw that our hypothetical, moderately affluent Briton requires on average about 195 kWh of energy a day to maintain the lifestyle to which he/she has become accustomed. (For comparison, 400 years ago, before the fossil‑fuelled industrial revolution, a person required on average about 20 kWh of energy a day.)
For a sustainable future, we need to wean ourselves off fossil fuels. The UK is well endowed with natural resources from which we could harvest renewable energy. Could we meet all our energy needs from renewables?
Sustainable Energy IV
This is the last article in my mini-series summarising David MacKay’s book “Sustainable Energy – without the hot air”. As we have seen previously, the typical, moderately affluent Briton directly or indirectly uses about 195 kWh of energy per day to sustain his/her lifestyle. And MacKay reckons that, per person, we will realistically only be able to get about 18 kWh of renewable energy per day from the country’s own resources.
