A FALTERING STEP TOWARDS ZERO CARBON 1 January 2014.

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1 A FALTERING STEP TOWARDS ZERO CARBON And an update on heat pumps It is common knowledge that we need to cut carbon emissions. Achieving the necessary cuts is going to be a big challenge for industry (in developing low carbon technologies), for society (in making lifestyle adjustments), and for democratic governments (in ensuring that emission targets are achieved). An elected government can make long term commitments to cut carbon emissions with impunity. There is too little accountability. If the same political party happens to be in power when eventually a long-term target is missed, they can blame the other lot, in power earlier, for not taking sufficient action. The taking of timely but unpopular action is very challenging for an elected government. There is too much temptation to prevaricate. An example of this can be seen in the government regulations for curtailing carbon emissions from new housing. Zero carbon new housing In 2006, the Labour government set the target that a decade later all new housing would have to be 'zero carbon'. This means that, over the course of a year, the net carbon emissions resulting from the energy used in such a house would be zero. This can be achieved in practice if the house uses very little energy for heating no central heating and it feeds surplus, carbon-free electricity into the grid (typically from PV panels). The target was to be met by revising the Building Regulations' Part L (Conservation of fuel and power). Part L limits the carbon emissions that are allowed from a new dwelling, and the limit was to be reduced in three steps: % reduction of emissions compared to 2006 Part L %,, %,, It was an extremely ambitious target, which left the biggest and most difficult step to the end. The first and easiest step, a 25% reduction, was implemented in So far, so good. But in 2011, the new Coalition Government changed the definition of 'zero carbon', thereby making it easier to achieve the target. The 'unregulated emissions' from householders' appliances are now to be omitted in the calculation of the emissions. There may be some sense in this a commercial housebuilder can hardly be held responsible for the use of appliances by future householders. Well, that's the argument though a nominal figure for appliance emissions could have been set to preserve the original intent. (Even for the calculation of regulated emissions which are due to space and water heating, ventilation, and lighting nominal figures are assumed about the requirements of future householders, eg, required temperatures.) The time has come for the reduction planned for 2013 a further 19% reduction of emissions compared to 2006 Part L. (This is equivalent to a 25% reduction compared to the current, 2010 Part L.) So last July, the Government announced the new requirements for Part L (for England). Unfortunately, the reduction is to be much smaller than originally planned not a 25% improvement on the 2010 figure, but a puny 6%. And its introduction is to be delayed until April Then, after eight years of the ten year time frame, we will be achieving cuts of 29.5% compared to 2006 standards leaving, in theory, a huge 70.5% cut to come after just another two years. A FALTERING STEP TOWARDS ZERO CARBON 1 January 2014.

2 You can be certain that the present government has no intention of meeting the ambitious, 2016 zero carbon target, even with its watered down definition of 'zero carbon'. (And if there is a Labour Government in 2016, you can be sure they, too, will miss the target with some justification blaming the Coalition Government that preceded them.) Unsurprisingly, there has been no public admission by the Coalition Government (which aspired to be the 'greenest government ever') that it has abandoned the 2016 zero carbon target. Instead, the spin in the government statement which announced the changes to Part L describes the changes as an important and technically meaningful step towards zero carbon homes. What was needed was a bold stride, and what we are getting is a faltering step. I can state quite confidently that the building regulations in place at the end of 2016 will not require zero carbon homes. It is not that the technologies required to achieve the zero carbon target are difficult. We know how to do it. Basically, energy requirements can be greatly reduced by lavish insulation, good airtightness, and Mechanical Ventilation with Heat Recovery. And carbon-free, solar energy can be harvested with PV and thermal panels, and windows. (Windows also lose energy, of course, though windows with a BFRC rating of 'A' are said to gain energy overall.) Because the UK's speculative housebuilders usually avoid technical innovations until forced to take them up by changes in the building regulations we now have to look to the Continent to see how to progress. Fortunately, the necessary technologies have been well developed there, and they are increasingly available here. Indeed, some selfbuilders have gone beyond zero, and built themselves carbon negative homes. Zero carbon or zero energy? Though eventually the government will publicly abandon the 2016 target of zero carbon for new housing, there is, fortunately, a back-stop position courtesy of the European Union. Since 2006, there has been a European Directive about the energy performance of buildings. The revised version of the directive requires that, by the end of 2020, all new buildings should be 'nearly zero energy'. That seems a rather vague phrase, but the directive goes on to say that the small amount of energy used by the building should be renewable (eg, from PV and thermal panels on the roof). It is open to debate whether we should be aiming for zero carbon or zero energy. For the selfbuilder, there are practical implications in the choice of target. For example, a house heated by a log stove might be zero carbon but not zero energy. The somewhat different objectives zero carbon or zero energy are reflected in two of the leading methodologies for assessing the performance of a house. The Standard Assessment Procedure (SAP) of Part L requires that the Dwelling Emission Rate of a house (a calculated figure for the carbon emissions resulting from the use of the house over a year) should be less than a Target Emission Rate (for a theoretical house of the same size). Presumably, by 2020 SAP will have to be amended so that it takes into account the 'nearly zero' energy requirement of the EU directive. (It might also continue to have emissions requirements.) In contrast, the PassivHaus Planning Package (PHPP) is based on energy: The energy required over a year for space heating and ventilation should not exceed 15 kwh per square metre of floor area. The total primary energy required over a year should not exceed 120 kwh per square metre of floor area. (This total includes the electricity used by domestic appliances.) A FALTERING STEP TOWARDS ZERO CARBON 2 January 2014.

3 120 kwh of primary energy is equivalent to 46 kwh of grid electricity. (46 = See the Footnote about primary energy.) So to get to 'zero-energy', a Passive House requires, in addition, some renewable energy input (eg, from PV and thermal panels). AN UNWELCOME INTERUPTION Some readers may have noticed that in the last few issues of the magazine my articles have not been as regular as normal. This happened after I wrote a draft article about multifoil insulation. BM TRADA, who have certified a particular multifoil, got some solicitors to threaten to sue myself and the magazine for libel if the article was published. As a stop-gap, the editor re-published three of my earlier articles about heat pumps. Since the Energy Saving Trust has recently published a new report about heat pumps, this may be an appropriate place to have a look at their latest findings. FIELD TRIALS OF HEAT PUMPS The Energy Savings Trust has been conducting field trials of heat pumps for several years. Their first report, Getting Warmer, was published in They had monitored 83 domestic heat pump systems in different parts of the UK for a year (54 Ground Source Heat Pumps and 29 Air Source Heat Pumps). The system efficiencies varied from a risable 1.2 to a creditable 3.2, with the average efficiency of the GSHP's being somewhat higher than that of the ASHP's. Poor installation seemed to be the cause of disappointing performances. The report made a number of recommendations, amongst which were: Keep the system simple. In particular, keep the controls simple so that the user can easily control the system. Have the whole system installed by one contractor, so that responsibility cannot be sloughed off amongst different subcontractors. Their follow-up report, The Heat is On, was published last August. The second field trial monitored 50 systems, of which 44 had been in the original trial. (Six new ASHP systems were added.) For the second trial, most of the original systems were modified. Some modifications were major (eg, replacing the heat pump itself), and some were minor. The modifications generally resulted in appreciable improvements, indicating that the initial installation had been unsatisfactory. The Seasonal Performance Factor Readers are doubtless aware of the importance of the Coefficient of Performance (COP) of a heat pump. But this is derived simply from a laboratory test of the pump itself. Moreover, a COP figure applies only to the given input and output temperatures. (If the sales literature doesn't give these temperatures be wary!) However, it is the overall efficiency of the whole system that matters to the householder. This is given by the 'System Performance Factor'. The SPF gives the number of kwh's of heat supplied by the system over a year for each kwh of electricity A FALTERING STEP TOWARDS ZERO CARBON 3 January 2014.

4 put into it. But confusingly, there are several ways of deciding what to include in the inputs and outputs. So there are four variants of the SPF H1, H2, H3 and H4. The electrical input for H2, for example, consists of the electricity used by: The heat pump itself; The pump in the ground loop (GSHP), or by the fans (ASHP). The electrical input for H4 includes, in addition, the electricity used by: Any pumps or fans in the heating system (eg, for UFH); Any immersion heater; Any electrical space heating. (The last two items of H4 might be used when the heat pump can't cope with demand.) There is a progressive order, so H1 results in the highest figure for the SPF (ie, the most flattering), and H4 results in the smallest SPF (the most dour) see the report if you want to know more details. (On average, SPFH2 figures were 10% higher than the corresponding SPFH4 figures.) Results of the second field trial The average system performance (SPFH4 ) for GSHP's was 2.8, and for ASHP's 2.4. There were wide variations see the chart. Nine out of 21 GSHP systems (ie, 42%) had an SPFH4 of a creditable 3 or more. Whereas only two out of 15 ASHP systems (ie, 13%) achieved that figure. (The six newly installed ASHP's performed significantly better than the ASHP's from the first field trial.) The highest performing system, a GSHP with an SPFH4 of 3.9, supplied heat for both UFH and domestic hot water. Seasonal Performance Factors of Air Source and Ground Source Heat Pumps (Source: Energy Savings Trust.) A FALTERING STEP TOWARDS ZERO CARBON 4 January 2014.

5 Finally, the report surmises that if the systems had been installed to the present standards of the Microgeneration Certificate Scheme (MCS), then performance figures would have been improved. FOOTNOTE: Primary Energy The term 'primary energy' alludes to the energy of a fuel in its original state in nature, eg, wood as a tree; coal under the ground. Some energy has to be expended in converting the natural fuel into a useful fuel at the point of use. The term is especially relevant to grid electricity, which is mostly derived from gas and coal. There are big energy losses in the conversion of these fuels into electricity, and some further losses in the distribution of electricity via the grid. The official figure is that, overall, 1kWh of grid electricity is derived from 2.6 kwh of primary energy. As more renewable electricity is fed into the grid, the Government's conversion figure, 2.6, should fall.) FURTHER INFO: Energy Saving Trust Download the reports of their heat pump field trials, Getting Warmer and The Heat is On. (A more technical report can also be downloaded.) Written Statement: Building Regulations Part L The Parliament UK website currently has a poor search facility, so here is the full address for the statement made on July 30. Lobbying by commercial housebuilders has been very successful! Words: Copyright article by Robert Matthews in SelfBuild & Design magazine, January, A FALTERING STEP TOWARDS ZERO CARBON 5 January 2014.