January 2016
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Shower Project July 2012
Guidance for Estimating Heat Capacity/ Generated/ Supplied
Introduction
The aim of this guidance is to assist heat suppliers in providing information under Regulation 3 of the Heat Network (Metering and Billing) Regulations 2014, Duty to notify. Specifically, Regulations 3-(1)(b)( i), (ii) and (iii). Templates have been made to aid with these notifications; this guidance refers to questions 17, 18 and 19 in the single notifications template or questions 18, 19 and 20 in the multiple notifications template.
An associated spreadsheet, the Heat Estimator, has been created with this guidance to further aid with calculations. Each worksheet in the Heat Estimator corresponds to the numbered methods described in this document. The Data worksheet is left visible so users can understand which values are being used.
This guidance has been created in order to support the broadest range of heat suppliers possible, it does not have to be used in order to comply with the legislation. A more thorough evaluation can be made but this guide shows an acceptable standard. Regulatory Delivery may ask a heat supplier to explain how values have been determined.
1. Estimated total installed heating/ hot water capacity (kW)
Heat Capacity is the maximum instantaneous output of a heat generator; it is a specification of the generator. Heat capacity is a measure of power and is measured in kilowatts (kW). Heat generated/ supplied over a time period is a measure of energy and is measured in kilowatt-hours (kWh). For example if a 20kW capacity boiler ran at maximum capacity for 2 hours then it would generate 40kWh of thermal energy.
Small domestic gas powered boilers range from about 4kW to 20kW, larger domestic boilers may have capacities up to 70kW. For commercial or industrial use, it is usual to run multiple boilers. If you have multiple heat generators, the total capacity is the sum of the individual capacities.
Some older boilers will state British Thermal Units per hour (BTU/hour) instead of kW.
1 BTU≈ 0.00029 kWh (Energy)
1 BTUhour≈0.00029kW (Power)
2. Estimated total heat/ hot water generated per calendar year (kWh)
Heat Generated is the heat input into the network over 12 months (not the amount of fuel being used).
Please use the table below to determine the appropriate method to estimate heat/ hot water generated.
Meter fitted on output of Heat Generator? / Use method:ü / 2.1
û / 2.2
As an alternative to using the Heat Estimator to estimate Heat Generated per calendar year, the calculation can be done manually using the appropriate method below. All energy contents and densities are based on the Higher Heating Value (HHV) also known as the the Gross Calorific Value (Gross CV).
2.2.1. Natural gas
The Heat Generated by a boiler utilising natural gas will be equal to:
Energy content of gas used kWh×boiler efficiency (%)
Normally the amount of gas used is measured as energy (kWh) but if only the volume is measured (m3) then the calorific value of the gas will have to be included:
Volume of gas used m3×Gross CVkWhm3×boiler efficiency (%)
2.2.1. Natural gas (cont.)
· The volume of gas used will be measured by a gas meter on the system or taken from an accurate bill.
· The gross calorific value of the natural gas depends on its methane content, typically around 97%[i], this would equate to about 10.91kWh/m3 [ii] or 0.3089kWh/ft3
· The boiler efficiency should be found on the technical specifications of the boiler, it would be expected to be around 85% [iii] for a modern condensing boiler.
2.2.2. Oil
The Heat Generated by a boiler utilising heating oil will be equal to:
Volume of oil used (l) ×Gross CVkWhl ×boiler efficiency (%)
· The gross CV of oil will be about 10.88kWh/litre [iv] [v]
· An oil burning boiler efficiency should be found on the technical specifications of the boiler. Older boilers will have efficiencies of around 70% and new condensing oil fired boilers have efficiencies of about 92% [vi]
2.2.3. Solid Fuel including Biomass and LPG
The Heat Generated by a boiler utilising solid fuel will be equal to:
Mass of fuel usedkg×Gross CV kWhkg×boiler efficiency%
· The gross CV of the biomass will depend on what fuel is being used. Common solid fuels and their associated specific energies are detailed in the table below. [vii]
Fuel / Gross CVkWh/kg
Domestic wood / 4.14
Wood pellets / 4.64
House coal / 8.36
Anthracite / 9.53
LPG / 13.72
· A solid fuel boiler efficiency is expected to be around 80% [viii]
2.2.4. Biogas
The Heat Generated by a boiler utilising biogas will be equal to:
Volume of gas used m3 ×Gross CVkWhm3 ×boiler efficiency %
· The gross CV of the biogas depends on its methane content, typically around 60 and 68% for household waste and agrifood respectively. This would equate to about 6.42kWh/m3 (0.1818kWh/ft3) for biogas from household waste and 7.28kWh/m3 (0.2061kWh/ft3) for biogas from agrifood.
· Biogas boilers are expected to about 75-90% efficient.[ix]
2.2.5. Electricity
The Heat Generated by an electric boiler will be equal to:
Electrical energy usedkWh×boiler efficiency%
· Electrical energy used will be measured by an electricity meter on the system.
· The boiler efficiency should be found on the technical specifications of the boiler, it would be expected to be around 90-100% [x]
3. Estimated total heat/ hot water supplied per calendar year (kWh)
Heat Supplied is the total amount of heat used by the customers of the system per calendar year. It should be lower than the Heat Generated due to the heat losses between the generator and the final customers.
Please use the table below to determine the appropriate method to estimate heat/hot water supplied per calendar year.
Individual meters fitted for each final customer? / Good knowledge about network efficiency? / Good knowledge about customer consumption? / Use method:ü / 3.1
û / ü / 3.2
û / û / ü / 3.3
û / û / û / 3.4
As an alternative to using the Heat Estimator to estimate Heat Supplied per calendar year, the calculation can be done manually using the method below.
The energy demand benchmarks are laid out in Assessing the cost effectiveness of individual metering: Energy Demand benchmarks . Benchmarks are based on space heating and hot water demand; it is assumed that 21% of overall heating demand is attributed to hot water[xi].
The estimated Heat Supplied for a domestic property is the sum of the annual domestic energy demand of each property on the network from Table 1. The consumption for each domestic property is categorised by age and type, this is then adjusted by regional weather correction factors from Table 3.
Example: A block of 6 flats built in 1965 in North East England (+11%)
8,653kWh×6 flats×1.0+0.11=57,629 kWh
The consumption for each non-domestic property type is categorised by use and floor space on Table 2, then adjusted for regional weather correction (this should be applied to only the proportion of the benchmark related to degree days).
Example: A general office (fossil-thermal prorated to degree days= 55%) in East Anglia (+4%) with a floor space of 90m2
120kWhm2×90m2×1.0+0.55×0.04 =11,038 kWh
Heat Network (Metering and Billing) Regulations 2014 Page 6 of 9
[i] http://www.biogas-renewable-energy.info/biogas_composition.html 24/02/2015
[ii]https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/447648/DUKES_2015_Annex_A.pdf 18/08/2015
[iii]https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/424254/heat_networks.pdf 26/03/2015
[iv] http://physics.info/energy-chemical/ 03/06/2015
[v] http://www.engineeringtoolbox.com/fuels-higher-calorific-values-d_169.html 18/08/2015
[vi] http://www.which.co.uk/home-and-garden/heating-water-and-electricity/guides/how-to-buy-the-best-boiler/oil-boilers/ 03/06/2015
[vii]https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/447648/DUKES_2015_Annex_A.pdf 18/08/2015
[viii] http://www.energysavingtrust.org.uk/domestic/content/our-calculations 24/02/2015
[ix] Peter Frost and Stephen Gilkinson, 27 MONTHS PERFORMANCE SUMMARY FOR ANAEROBIC DIGESTION OF DAIRY COW SLURRY AT AFBI HILLSBOROUGH, June 2011
[x]
[xi]
Contact Details
Enforcement Authority
Regulatory Delivery
Stanton Avenue
Teddington
London
TW11 0JZ
Enquiry Telephone: 020 8943 7227
Website: www.gov.uk/heat-networks
Email:
Enquiry System: www.rohs.bis.gov.uk/enquiry.aspx
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