heat load calculation

1. Muhamad farid bin ridzuan Topics covered • Heat load/Heat gain • Precision Air Conditioning(PAC)

2. Heat load/heat gain A building or room gains heat from many sources. Inside occupants, computers, copiers, machinery, and lighting all produce heat. Warm air from outside enters through open doors and windows, or as ‘leakage’ though the structure. The biggest source of heat is solar radiation from the sun, beating down on the roof and walls, and pouring through the windows, heating internal surfaces.

3. The sum of all the previous heat sources is known as the heat gain (or heat load) of the building, and is expressed either in BTU (British Thermal Units) or Kw (Kilowatts). • For an air conditioner to cool a room or building its output must be greater than the heat gain. It is important before purchasing an air conditioner that a heat load calculation is performed to ensure it is big enough for the intended application.

4. Recommended btu for north/south facing windows North/South windows

5. Recommended btu for east/west facing windows East/West windows

6. Example of room

7. Example of Heat gain factors • 4 workers in the space room • 4’ x 2’ windows of south and north • No curtains • Have shading • Printer x 1 ea (100 watts) • 60W light bulb x 1 ea (60W) • 100W light bulb x 1 ea (100W) • Desktop computer x 4 ea (150W x 4 ) • Photocopier x 1 ea (150W)

8. Room size BTU • BTU size room = Length x Width x 337 (in m) = 6.1 x 4.572 x 337 = 9398 m^2

9. Windows BTU • This is for north and south facing windows. Total BTU for windows = 194.04 + 1023 = 1217.04 BTU

10. Occupant btu • Calculate the heat generated by occupants, allow 400 BTU per person • 4 workers and 400 per person BTU Occupants BTU = 4 x 400 = 1600 BTU • Because person also released heat.

11. Machine and btu • Calculate the heat generated by each item of machinery - copiers, computers, ovens etc. Find the power in watts for each item. • Equipment BTU = Printer x 1 ea (100 watts) + Desktop computer x 4 ea (150W x 4 ) + Photocopier x 1 ea (150W) x 3.5 = 100 + 600 + 150 = 850 W x 3.5 = 2975 BTU

12. Lighting btu • Calculate the heat generated by lighting Lighting BTU = total light watts x 4 .25 = (60W light bulb x 1 ea (60W) + 100W light bulb x 1 ea (100W) ) x 4.25 = 680 BTU

13. Total heat load • Add the above together to find the total heat load • Total heat load BTU = Area BTU + Total Window BTU + Occupant BTU + Equipment BTU + Lighting BTU • Total heat load BTU = 9398 + 1217.04 + 1600 + 2975 + 680 = 15870.04 BTU

14. 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 a/c units required = Total heat load BTU / Cooling capacity BTU = 15870.04 BTU / 10000 = 1.5 -> 2 A/C required for the room size

15. Simple calculation 1 • Calculate the size of the room in ft^3 C1 = 20ft x 15ft x 10ft = 3000ft^3 and times with 6 = 18000 BTU • Find the BTU of occupants, example 4 occupants (400 per person) C2 = 4 x 400 = 1600 BTU Estimate of cooling capacity needed = C1 + C2 = 18000 + 1600 = 19600 BTU Cooling capacity 1hp = 10000 BTU 1.5 hp = 15000 BTU 2 HP = 20000 BTU 2.5 hp = 27000 BTU

16. Simple calculation 2 • Calculate the size of the room in ft^3 C1 = 20ft x 15ft x 60(standard) = 18000 BTU • Find the BTU of occupants, example 4 occupants (400 per person) C2 = 4 x 400 = 1600 BTU Estimate of cooling capacity needed = C1 + C2 = 18000 + 1600 = 19600 BTU Cooling capacity 1hp = 10000 BTU 1.5 hp = 15000 BTU 2 HP = 20000 BTU 2.5 hp = 27000 BTU

17. Precision Air COnditioning • What is Precision Air-Conditioning (PAC)? PAC or ‘close control air conditioning’ are a system that is installed in most server rooms. These systems control temperature, humidity and particle filtration within tight tolerances 24 hours a day and can be remotely monitored. They can have built-in automatic alerts when conditions within the server room move outside defined tolerances. Air conditioning designs for most computer or server rooms will vary depending on various design considerations, but they are generally one of two types: "up-flow" and "down-flow" configurations.

18. Why we need the pac? • Computer equipment generates heat, and is sensitive to heat, humidity, and dust, but also the need for very high resilience and failover requirements. Maintaining a stable temperature and humidity within tight tolerances is critical to IT system reliability. • Precision air conditioners are a must, at every location where network/server gear worth thousands of dollars (and more) are located.

19. How does Pac works?

20. Advantages of pac over standard ac • Precise and quick processor-based temperature control, to keep your IT equipment at the right temperature, always. • Precise humidity control. Electronic devices require a steady level of humidity for proper functioning. Both high/low humidity levels can impede them on the long run. • Precision air conditioners are designed to manage high levels of sensible heat (heat without humidity, emanated by machines) while comfort/standard air conditioners are designed to manage latent heat (heat with humidity, emanated by people). • Precision air conditioners demonstrate better air distribution.

21. Training on Data center cooling technique - How Precision Air Conditioners work - YouTube.MKV

22. conclusion • Today’s highly technology rooms requires precise and a stable environment so that the sensitive products could function properly. • A standard comfort air conditioning is not suitable for such rooms and using it can result in element failure and frequent system shutdowns. • For such situations, precision air conditioning is recommended as it maintains the humidity as well as temperature in very low range. • It offers environment stability which is required by the sensitive equipment; hence you don’t have to face expensive downtime in your business.

23. Thank you….