How to do Heat Load Calculations in HVAC? - Simple Method to do Heat Load Calculation

How to do Heat Load Calculations in HVAC?

 The estimation of heat load can assist with deciding how much energy your framework uses and what changes should be made to keep temperatures agreeable for tenants and hardware. Ascertaining how much cooling required at different burdens assists you with adjusting the expense adequacy of HVAC frameworks against the solace needs of your office.

                Heat Load Calculation considers how much energy a framework utilizes over the long run and can give helpful data about how well your framework is performing. An appropriately working cooling unit ought to give satisfactory chilling while at the same time keeping energy utilization off. An ineffectively measured unit might utilize a lot of force or neglect to sufficiently cool your home.

                Heat load computation in HVAC alludes to how much hotness that goes into a space from the climate. This is estimated in BTUs each hour (Btu/h). The Btu/h estimate is then used to work out the complete energy consumed by the framework (i.e., Heating, ventilation and cooling) to keep a particular temperature in a space. This computation is regularly done utilizing a heat-load number calculator or a room simulation computer program.

                 An ordinary private home might utilize roughly 1,000 Btu/h. Business structures normally consume somewhere in the range of 2,500 - 5,000 Btu/hr. Schools will more often have higher loads because of countless students who are completely found together in one spot. Emergency clinics are known to have high hotness loads, particularly in the event that these offices don't give their own cooling frameworks. Be that as it may, medical clinics seldom work at temperatures above 80°F, while other business structures can be a lot more heated relying on the kind of industry and the number of individuals work in them 24 hours out of every day.

There are many ways of doing Heat Load Calculations. Manual and with the assistance of Softwares. In this post we will see a manual technique to do heat load calculations.

            A structure or room acquires heat from many sources. Inside tenants, computers, copiers, apparatus and lighting, everything produces heat. Warm air from outside enters through open entryways and windows, or as 'spillage' through structure. But, the greatest source of hotness is sunlight based radiation from the sun, whipping on the rooftop and the walls, and pouring through the windows, warming the inside surfaces.

        The addition of every one of these hotness sources is known as the hotness gain (or Heat Load) of the structure, and is communicated either in BTU (British Thermal Units) or Kw(Kilowatts). For a forced air system (air conditioner) to cool a room or a structure, its result should be more prominent than the hotness gain. It is significant prior to buying an air conditioning system, that a Heat Load Calculation is performed to guarantee that it is large enough for the planned application.

Heat Load Calculations:

            There are a few distinct techniques for calculating the heat load for a given region:

Quick Calculation For Offices:

            For workplaces(offices) with normal insulation and lighting, 2/3 tenants and 3/4 personal computers and a printer, the accompanying estimation will do the trick:

            Heat Load (Btu) = Length (ft) x Width (ft) x Height (ft) x 4

In Metric System:

            Heat Load (Btu) = Length (m) x Width (m) x Height (m) x 141

For each extra inhabitant add 500 Btu. Assuming there are any extra sources of hotness, for example floor to roof south-bound windows, or hardware that produces bunch of hotness. The above strategy will misjudge the heat load. In which case, the accompanying technique ought to be utilized all things being equal.

A more precise heat load calculation for a room or building:

            The hotness gain of a room or building relies upon, the size of the area being air conditioned, the size and orientation of the windows and whether they have shading, the quantity of tenants, heat created by machinery and equipments, heat produced by lighting. By working out the hotness gain from every individual thing and adding them together, an exact heat load figure could be calculated.

Now we will see the step by step procedure to calculate the heat load using the above said method.

Step 1: Calculate the area in square feet of the space to be cooled, and multiply by 31.25 

                Area Btu = Length (ft) x Width (ft) x 31.25

Step 2: Calculate the heat gain through the windows. If the windows don't have shading multiply the result by 1.4

                North Window Btu = Area of North Facing Windows (sq m) x 164

If no shading, North Window Btu = North Window Btu x 1.4

                South Window Btu = Area of South Facing Windows (sq m) x 868

If no shading, South Window Btu = South Window Btu x 1.4

Add the results together.

                        Total Window Btu = North Window Btu + South Window Btu

Step 3: Calculate the heat generated by occupants, allow 600 Btu per person.

                        Occupant Btu = Number of people x 600

Step 4: Calculate the heat generated by each item of machinery like copiers. computers, ovens, etc. Find the power in watts for each item, add them together and multiply by 3.4

                        Equipment Btu = Total Equipment watts x 3.4

Step 5: Calculate the heat generated by lighting. Find the total wattage for all lighting and multiply by 4.25

                        Lighting Btu = Total lighting watts x 4.25

Step 6: Add all the Btu loads together to find the Total Heat Load.

                        Total Heat Load Btu = Area Btu + Total Window Btu + Occupant Btu + Equipment Btu + Lighting Btu.

Step 7: Divide the heat load by the cooling capacity of the air conditioning unit in Btu, to determine how many air conditioners are needed. 

                    Number of AC units required = Total Heat Load Btu / Cooling Capacity Btu

Manually calculating the size of an air conditioner required can appear to be a complicated task, but for beginners its a boon. Later on once they learn how it works, they can switch to software method of calculating Heat Load.