Further Guidance
The heating hours and required internal temperatures in DEAP are based on the requirements of a typical household. The schedule is as follows.
This standardised schedule represents a total heating period of 56 hours per week. The required (set point) internal temperatures during heating periods are:
During heating hours, the required mean internal temperature of the dwelling is calculated as the average of the set-point temperatures in the living area and in the rest of the dwelling, weighted by floor area.
The mean internal temperature of the dwelling during periods when heating is required is calculated as a floor area weighted average of set point temperatures in the living area and the rest of the dwelling. The effect of intermittent heating on the mean internal temperature is calculated using the dwelling’s internal heat capacity. A notional ideal heating system is first assumed, i.e., provides just enough heat to precisely maintain required temperatures during heating hours. An ideal heating system has perfect control and responsiveness, and infinite heat output capacity. The mean internal temperature is calculated for each month, taking account of monthly mean external temperatures. The effects of imperfect control and heating system responsiveness are subsequently dealt with based on data entered under heating controls.
[Net Space Heat Demand calculation in DEAP]
The space heat use is defined in IS EN 13790 as the heat delivered to the heated space by an ideal heating system to maintain the set point temperature during a given period of time. The DEAP calculation of space heat use is carried out on a monthly basis based on the procedure described in IS EN 13790. A single zone calculation is used, using a single average value of mean internal temperature as described above.
For each month:
The utilisation factor calculation does not reflect the responsiveness of the heating system. A slow response heating system can significantly reduce the usefulness of fluctuating heat gains.
In DEAP, the heating season is defined as running from October to May inclusive. The annual space heat use is the sum of monthly values for these eight months.
The annual energy required from the actual (as distinct from notional ideal) heating system for space heating purposes is calculated, taking account not only of annual space heat use as described in above, but also imperfect control and responsiveness of the heating system, and additional heat loss associated with under floor heating where applicable. This is termed the annual space heating requirement.
The benefit of heat gains associated with electricity consumption by heating system pumps and fans is also included, applying an average utilisation factor as determined when calculating the net space heat demand.
The quantity of fuel or electric energy required to meet the annual space heating requirement is calculated using the seasonal efficiency of the space heating system(s) in the dwelling, obtained from the HARP database, certified test data, Ecodesign data where applicable or from Table 4.4 or Table 4.5. A similar calculation is carried out in respect of hot water heating, applying results based on entries in the ’Water heating’ tab.
Calculations are completed based on group/district, or individual heating systems, depending on whether one or more dwellings are heated by the space heating system specified in DEAP.
All heat sources using combustion must have the gross seasonal efficiency specified. The conversion from net efficiency to gross efficiency is specified in the relevant appendices.
The calorific value of a fuel is the heat released when one kilogram of the fuel is burnt completely in excess air, under specified conditions, and the combustion products cooled back down to the initial (room) temperature. If the water vapour in the combustion products remains as vapour, the heat released is the net calorific value, but if it is condensed to liquid water, releasing its latent heat of vaporisation, the total heat released is the gross calorific value.
It is assumed that the dwelling has heating systems capable of heating the entire dwelling. Calculations are on the basis of a main heating system and secondary heaters as described in primary and secondary heating systems. This guidance also covers whether secondary heating is to be specified or not. The apportionment of heat supplied from the main and secondary systems is given in Table 4.14.
Direct acting electric heaters should be selected for new dwellings with no heating system specified.
For group/community heating schemes and combined heat and power, see Group Heating. A heating system supplying more than one dwelling should be regarded as a group scheme. This includes schemes for blocks of flats where the heat source is located within the boundaries of the site. If the heat source is located outside the boundaries of the site, the heating system should be regarded as district heating.
For an electric combined primary storage unit (CPSU), see here. For heat pumps, see here.
Table 4.12 - Gains from fans and pumps
| Function | Gains (W) |
|---|---|
| Central heating pump in heated space a) | 10 |
| Oil boiler pump, inside dwelling b) | 10 |
| Warm air or fan coil heating system fans a) c) | 0.06 × V |
| Balanced whole house mechanical ventilation fans | SFP × 0.06 × V |
Notes:
a) Does not apply to group heating.
b) Only for boiler providing main heating. In addition to central heating pump, but not if oil pump is outside dwelling.
c) If the heating system is a warm air unit and there is whole house ventilation, the gains for warm air circulation should not be included in addition to the gains for mechanical ventilation. V is the volume of the dwelling. Source: SAP 2005. The electric fan on fan coil radiators is recorded in the DEAP ‘Space heating: pumps and fans’ tab.
Table 4.13 - Evidence requirements for space and water heating sources
| Space and water heat sources | ||
|---|---|---|
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Guidance on re-use of data for Space heating: Space and water heat sources can be found here |
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| Data Entry Item | Guidance | Documentary Evidence |
| Main Space and Water heating system |
DEAP Manual rules apply when determining heating system efficiencies. Details must be recorded on the DEAP Survey Form. Photographs of the heating system (e.g., boiler, heat pump, etc.) must be taken to support data inputs. Photographs of nameplates with make and model number can also be taken to support non-default efficiencies. Heating system manuals or installation certificates can also be copied and used as supporting data. In the absence of supporting data, default efficiencies in Table 4.4/4.5 in DEAP manual must be used. |
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| Secondary heating system |
DEAP Manual rules apply when determining secondary heating system efficiencies. Details must be recorded on the DEAP Survey Form. Photographs of the secondary heating system (e.g., room heater, etc.) must be taken to support data inputs. Photographs of nameplates with make and model number can also be taken to support non-default efficiencies. Heating system manuals or installation certificates can also be copied and used as supporting data. In the absence of supporting data, default efficiencies in Table 4.4/4.5 in DEAP manual must be used. |
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| Fuel data |
Details must be recorded on the DEAP Survey Form. If a solid fuel burner can burn more than one type of fuel, select solid multi-fuel as the fuel type |
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| Combined Heat and Power (CHP) for group or individual heating system. | Details must be recorded on the DEAP Survey Form. Where available, efficiency data is taken from test reports based on a national standard or the CHP Directive 2004/8/EC. Photographs of the CHP system must be taken to support data inputs. |
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