Page 111 - GRIHA Manual Volume III - Introduction to National Rating System
P. 111
104 GRIHA Manual: Volume 3
Table 2 Hot water calculations for a hostel
Type of use Occupants Hot water requirement per Total hot water requirement
head / day (litres) per day (litres)
Bathing 500 15 7500
Washing clothes 50 10 5000
Mess 500 5 +5 (For 2 meals a day) 5000
Total hot water requirement 17 500
Step 2:
Energy requirement for heating water
Calculate to find out the total energy required to meet the hot water requirements of the building
(except for space heating). These calculations can also be done using computer software.
Given below is a table specifying total energy required to meet the hot water requirements of a
building using three different types of fuels.
Table 3 Energy required for meeting the hot water requirements of a building
Fuel type Electricity HSD LPG
Caloriic value (kcal/kg) 10 100 11 000
Caloriic value (kcal/litre) 10 000 10 800
Caloriic value (kcal/kWh) 861
Conversion eficiency 90% 90% 90%
Combustion eficiency 100% 85% 70%
Quantity of fuel required (litres) 13 725 15 432
Quantity of fuel required (kWh) 1 35 500
Step 3
Design of renewable energy-based hot water system
Depending on the total hot water requirements of the building, design a renewable energy-based
system that can cater to atleast some portion of this hot water demand. Softwares are available for
conducting these calculations.
Following is a snapshot of the software that is used for sizing a renewable hot water system
and for predicting the annual energy generation by the installed renewable system. The software
also provides the total energy requirement for heating the given quantity of water. In the example
given below, a solar-evacuated tube-collector-based water heating system has been designed for a
building with daily hot water requirement of 50 000 litres. As shown in the figure, the total energy
required for heating this quantity of water is 742.64 MWh and the renewable energy generated by
the designed system is 608.55 MWh.
Table 2 Hot water calculations for a hostel
Type of use Occupants Hot water requirement per Total hot water requirement
head / day (litres) per day (litres)
Bathing 500 15 7500
Washing clothes 50 10 5000
Mess 500 5 +5 (For 2 meals a day) 5000
Total hot water requirement 17 500
Step 2:
Energy requirement for heating water
Calculate to find out the total energy required to meet the hot water requirements of the building
(except for space heating). These calculations can also be done using computer software.
Given below is a table specifying total energy required to meet the hot water requirements of a
building using three different types of fuels.
Table 3 Energy required for meeting the hot water requirements of a building
Fuel type Electricity HSD LPG
Caloriic value (kcal/kg) 10 100 11 000
Caloriic value (kcal/litre) 10 000 10 800
Caloriic value (kcal/kWh) 861
Conversion eficiency 90% 90% 90%
Combustion eficiency 100% 85% 70%
Quantity of fuel required (litres) 13 725 15 432
Quantity of fuel required (kWh) 1 35 500
Step 3
Design of renewable energy-based hot water system
Depending on the total hot water requirements of the building, design a renewable energy-based
system that can cater to atleast some portion of this hot water demand. Softwares are available for
conducting these calculations.
Following is a snapshot of the software that is used for sizing a renewable hot water system
and for predicting the annual energy generation by the installed renewable system. The software
also provides the total energy requirement for heating the given quantity of water. In the example
given below, a solar-evacuated tube-collector-based water heating system has been designed for a
building with daily hot water requirement of 50 000 litres. As shown in the figure, the total energy
required for heating this quantity of water is 742.64 MWh and the renewable energy generated by
the designed system is 608.55 MWh.
