HVAC Refresher – Facilities Standard for the Building Services (Part 2) A. Bhatia Course Content SECTION # 1: RULES OF THUMB AIR-CONDITIONING CAPACITY 1) A ton of refrigeration (1TR) signifies the ability of air-conditioning equipment to extract heat @ 12000 Btu/hr. ASHARE (American Society of Heating, Refrigeration and Air-conditioning. Aug 26, 2016 On the horizontal axis, I plotted the conditioned floor area, in square feet. On the vertical axis, I plotted the cooling load divided by the floor area, or square feet per ton. Remember, when HVAC contractors use rules of thumb to size air conditioners, they usually pick a number between 400 and 600 square feet per ton. Here's what our data show.
Every HVAC designer needs some handy empirical data for use in approximating loads and equipment sizes during the early conceptual stages of the design process. These are typically square feet per ton for cooling, Btu per square foot for heating, and cubic feet per minute per square foot for air-handling equipment. The values used will vary with climate and application and are always tempered by experience. These numbers can also be used as check figures during the detailed calculation procedure to alert the designer to unusual conditions or computational errors. As an example only, the cooling load values in Table 3.1 are based on traditional empirical data and will not be applicable in all cases. Energy conserving practice in envelope construction, in lighting design, and in system design has resulted in decreased loads in many cases. But increased use of personal computers and other appliances has the opposite effect of increasing the air conditioning requirements. Designers must develop their own site-specific data if the data are to be reliable.
Building type | ft 2/ton |
---|---|
Residence | 600 700 |
Classroom | 200 250 |
General office | 300 350 |
Conference room | 100 200 |
Bowling alley | a |
Clean room | 100 300 b |
Hospital patient room | 300 350 c |
Manufacturing | 250 350 d |
Areans, etc. | 150 200 |
Hotel meeting room | 200 250 |
Data processing room | 80 100 e |
aOne ton per lane, plus additional for spectator areas, food service, etc. bEight to 10 (ft 3/min)/ft 2 required. cMost codes do... |
Every HVAC designer needs some handy empirical data for use in approximating loads and equipment sizes during the early conceptual stages of the design process. These are typically square feet per ton for cooling, Btu per square foot for heating, and cubic feet per minute per square foot for air-handling equipment. The values used will vary with climate and application and are always tempered by experience. These numbers can also be used as check figures during the detailed calculation procedure to alert the designer to unusual conditions or computational errors. As an example only, the cooling load values in Table 3.1 are based on traditional empirical data and will not be applicable in all cases. Energy conserving practice in envelope construction, in lighting design, and in system design has resulted in decreased loads in many cases. But increased use of personal computers and other appliances has the opposite effect of increasing the air conditioning requirements. Designers must develop their own site-specific data if the data are to be reliable.
Building type | ft 2/ton |
---|---|
Residence | 600 700 |
Classroom | 200 250 |
General office | 300 350 |
Conference room | 100 200 |
Bowling alley | a |
Clean room | 100 300 b |
Hospital patient room | 300 350 c |
Manufacturing | 250 350 d |
Areans, etc. | 150 200 |
Hotel meeting room | 200 250 |
Data processing room | 80 100 e |
aOne ton per lane, plus additional for spectator areas, food service, etc. bEight to 10 (ft 3/min)/ft 2 required. cMost codes do... |