Discussion

I am a little unsure how to convert my gas HH kWh into thermal load.

The equation I have been looking at is the following:

Annual Energy Input (kJ) = (Boiler heat output (kW) x hrs/day x days/year x 3600 x Seasonal Efficiency) / (Thermal Efficiency x Part-Load Efficiency)

Can I transpose this to the following:

Thermal Requirement (kWh) = ((Energy Input (kWh) x (Thermal Efficiency x Part Load Efficiency)) / Seasonal Efficiency

Then,

Thermal Load (kW) = Thermal Requirement (kWh) x Hours

Any help greatly appreciated.

Many thanks

Craig

Your calculation is missing network loading factor. This loading factor is derived from degree days data using maximum possible degree days per year and site nominal degree days.After completing the annual gas consumpton calc using load factor, the final formula should look like this:

Avg gas consumption per annum[in kWh] =[(avg gas consumed per yr, in m3)x (volume conversion factor,1.02264) x (gas calorific value, MJ/m3)]/3.6

You will get the results in Kwh/yr.Use gross calorific value for gas i.e. 38.7 MJ/m3. Trust this helps.

Atiq

slight clarification, in your case you need to reverse the step to get the plant sizes. There is a danger in doing a back calculation in this way. You will need to fix the plant multiplication factor and declare how much you would choose. Plant multiplication factor can be found in CIBSE guide A for various type of buildings. However, you can always choose an optimum one, google will be your friend.

if you are unsure about what i have said, pm me so that i can show you a practical calc. unfortunately i can not attach a file in this forum.