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Heating costs calculator

Calculation of heating oil savings of a house with defined glass area – calculated by:

Expected glass lifetime

Cost of resources (price per unit)

Window area

SE – SW
NW – NE
Other

Old glass

New glass

Other data

Losses & solar gains

Results

Heating oil savings

Heizöl

Natural gas savings

Erdgas

Download/print results as PDF

How was it calculated?

Calculation of energy savings by replacing glass

The energy savings are calculated according to the specifications of the GEG 2020 (German Building Energy Act) for the reference climate in Germany.

Annual heating requirement Qh:

Qh = FGt x (HT + HV) - μHP x (QS + Qi)

FGt: Degree day factor according to the German Energy Conservation Regulations for Buildings (EnEV) for the reference climate in Germany = 66.12 kKh/a
HT: Specific transmission heat loss – here heat transmittance coefficient of the glazing Ug x Aw (window area) – an average frame proportion of 30% is assumed. Enhanced frame materials are not the subject of consideration.
HV: Specific ventilation heat loss – assumed constant here (ΔHV = 0)
μHP: Degree of utilisation of heat gains according to EnEV = 0.95
QS: Useful solar heat gains. These gains are derived in relation to the orientation of the glazing to the compass direction Is,HP as well as to a reduction factor to account for the frame proportion (30%) and glazing contamination. Qs = 0.567 Is,HP (as per EnEV); assumed frames are not exchanged
Qi: Internal heat gains – assumed constant here (ΔQi = 0)
Qh': Heating energy requirement Qh' = FGt (HT + HV)
Ug: Heat transmittance coefficient of glazing
g: Solar heat gain coefficient of glazing
Is,HP: Medium radiation intensity I in the considered heating period (HP) in kWh/m2·a

Calculation of heating energy savings

Calorific value of ELK heating oil 10.7 kWh/l – reduced by factor 0.943 according to EnEV = 10.09
Heating oil savings in litres per heating period according to EnEV = Qh/10.09
Heating assumption: low-temperature boiler outside the thermal envelope; flow/return temp. 70 °C/55 °C; risers and distribution inside the thermal envelope; controlled pump - ep = 1.74
Conversion factor heating oil/natural gas in m3 = 1/1.15
CO2 - equivalent of heating oil (LT heating) 0.372 kg/kWh; or of natural gas (LT heating) 0.297 kg/kWh
[GEMIS: http://www.energieverbraucher.de]
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