Thermal Envelopes and Heating Systems

Transcription

1 Thermal Envelopes and Heating Systems UCL, 29 November 2011 David Olivier

2 What I Shall Talk About Greater Energy Efficiency in Heating Concern over Current Policy Case Studies/Proposed Projects, UK & Denmark More detail in the forthcoming report: LESS IS MORE: Energy Security After Oil. AECB, the Sustainable Building Association.

3 Greater Energy Efficiency - Heating Reduce the quantity of heat consumed; e.g. insulate the walls, upgrade the windows and draughtproof a building to reduce its heat loss. Some allowance in current policy. Match the quality of energy supplied to the demand; e.g., replace a gas-fired heat-only boiler or electric resistance heating by waste heat from gas CHP or perhaps heat pumps. But current policy stresses decarbonisation of electricity. The combination. Can reduce consumption of high-grade energy and CO 2 emissions by 99%. But just 95% would be very satisfactory.

4 Lower Heat Consumption kwh/m 2.yr. Good and best practice reduces emissions 95-97% versus worst practice, 70-88% vs. 2000s average practice. Sources: Space Heat Consumption of a Dwelling, Different Heat Loss Levels Calculated for a 120 m 2 two-storey wellheated detached house, using PHPP Old, uninsulated Typical 2000s MINERGIE/Silver Low En. Class 2 Low En. Class 1 Passivhaus Old uninsulated and 2000s construction - author s estimate MINERGIE - Swiss government standard, IP jointly owned by the 26 cantons Silver - AECB, the Sustainable Bldgs Assocn. Low Energy Class I and II - Danish government standards Passivhaus - standard - PHI, Darmstadt, Germany

5 Lower-CO 2 Heat Good practice reduces emissions 80-90% versus current practice. 1.2 kg CO2 equiv. per kwh of heat GHG Emissions of Various Space and Water Heating Systems woodand coalfired boilers electric resistance heating NOTE: In line with recent work on the subject, this chart includes the combustion CO 2 emissions of biomass heating systems elec. heat pumps oil and gas boilers CHP/DH systems 0.2 0

6 Scope for Enhanced Thermal Comfort Heat consumption kwh/m 2.yr. Red - uninsulated existing stock Orange - estd. 2000s construction Blue - MINERGIE or Silver Green - Low Energy Class I Space Heat Consumption Versus Mean Internal Temperature 120 m 2 detached house UK heating season mean temp. Danish mean heating season temp Mean daily temperature o C

7 Rural Fuel Poverty? Fuel cost, oil condensing boiler. Excludes servicing/maintenance, DHW and household electricity costs Oil cost, ex-tax and duty /yr. Red - uninsulated existing stock Orange - estd. 2000s construction Blue - MINERGIE or Silver Green - Passivhaus Space Heating Fuel Cost Versus Mean Internal Temperature 120 m 2 detached house Mean daily temperature o C

8 Space Heating Load Duration Curve Danish 145 m 2 detached bungalow. Low Energy Class 1; i.e., near to Passivhaus Standard. All space heating load duration curves have the same basic shape. A lower specific heat loss, or lower cooling time constant, tends to reduce the load factor. These are close to daily mean values, not hourly values.

9 Concerns over UK Policy Energy Economics - Money Meets Energy The resource demands of different technologies vary widely. Energy options are being pursued which are up to 30 times more capital-intensive than today s offshore oil supply ( per delivered kw). A senior oil industry representative... stated that 2004 was the inflection point when global conventional oil production plateaued and oil stopped being cheap. The speaker affirmed that the supply flow is more important than reserves and that we know that $150[/barrel] oil breaks the machine so that the global economy cannot function above that price. It does not matter how much oil is left if we can t afford it. Account of 2010 peak oil summit. Unless we are selective and invest promptly in high-eroei resources, we may risk perpetuating the economic problems. Money Meets Energy: An Exponential Economics Primer pdf (November 2010).

10 Concerns over UK Policy Future Network Stability 94% of domestic space heating is from natural gas, oil, LPG and coal - in built-up areas, mainly gas; in rural areas, mainly oil. The gas network allows considerable energy storage. Heat networks, if used, can increase the pumping rate and the flow temperature to meet peaks. Bulk heat storage is cheap; some small cities have 100,000 m 3 hot water stores on their DH network. With electricity networks, storage is costly and network losses rise with load.

11 1970s Low-Rise Dwellings, London Cavity-walled, solid ground-floored housing before and after proposed TSB RFF retrofit. CO 2 emissions would fall 82% at ~ 10k per dwelling in widespread use for the thermal measures. Construction probably typical of 30-40% of existing dwelling stock. CWI and roof insulation with airtight material Gas 500 kw(e) recip. engine CHP, extend existing scheme, add summer solar Reglaze existing windows when sealed units wear out MEV not MVHR Highly energy-efficient lights, A++ appliances & pumps, including CHP heat for clothes drying Highly-insulated new DHW tank and piping with improved heat exchanger

12 MACC for Measures Analysed Existing Typical Urban or Suburban Semi-Detached House COST OF MEASURE ( /tonne) NOTES: 1 More energy-efficient hot-fill dishwasher 2 More energy-efficient lighting 3 More energy-efficient refrigerator-freezer 4 Cavity wall insulation, 50 mm PU foam 5 More energy-efficient LED TVs 6 More energy-efficient hot-fill washing machine 7 Condensing boiler and compensation controls 8 Windows - replace failing doubled-glazed sealed units by argon-filled low-e warmedge sealed units 9 More energy-efficient central heating pump 10 Gas-fired combined heat and power and heat mains 11 Windows - upgrade replacement sealed units to optimum low-e coating 12 Horizontal external perimeter insulation of ground floor, 50 mm XPS 13 MEV, miscell. draughtproofing and replace electric clothes drying by CHP heat 14 Roof, add 50 mm PU foam between rafters 15 Add solar to DH system 16 Insulate DHW system 17 External wall insulation, increase from 50 to 100 mm graphitised EPS 18 Roof, increase from 50 to 100 mm PU foam 19 Roof increase from 100 to 120 mm PU foam, with 20 mm covering rafters 20 Perimeter insulation, increase from 50 to 100 mm XPS 21 External wall insulation, increase from 100 to 150 mm EPS 22 Windows, replacement high-performance double glazing 23 External wall insulation, install50 mm graphitised EPS, directly-rendered NOTE: Base case emissions = 8.50 tonnes/year. CUMULATIVE SAVING (tonnes/year)

13 82% Cut in CO 2 Emissions Before Allowing for Electricity Decarbonisation 300 Before Energy electricity UNITS: Delivered energy in kwh/m 2 yr. CO 2 emissions in kg/m 2 yr. 150 After 100 gas CO 2 Energy electricity electricity 50 0 heat gas CO 2 heat electricity

14 The Small Town of Marstal 4,600 people, 2,000 houses Headed towards 33,000 m 2 of solar collectors in the DH system Plus sheep... Pictures: Courtesy Marstal Fjernwärme AMBA.

15 Cost of Solar Heat Versus System Size 20of%20large-scale%20solar%20thermal%20plants.pdf Heat cost (FOB) falls from 17 to 1.6 p/kwh as system size rises from 50 to 20,000 m 2. Refers to heat at 85 o C, return at around 30 o C.

16 For further information: David Olivier, BSc MEI MASHRAE Principal ENERGY ADVISORY ASSOCIATES 1 Moores Cottages, Bircher, Leominster, Herefordshire, England, HR6 0AX Tel.: (01568) info[at]energyadvisoryassociates.co.uk Web: EAA All rights reserved. Reproduction permitted for non-commercial use only subject to prominent acknowledgement of the source, including all the copyright holders of photographs or charts. All other uses strictly forbidden without the prior written permission of the publisher.