BTU need for a 60′(w) x 100′(l) x 12′(h) building.
toffee
| Posted in Energy Efficiency and Durability on
This is hypothetical building, with R40 roof, and R38 wall on concrete slab foundation/floor, no window. Basically a warehouse in the desert with daytime high of 115F but need the interior to be around 73F.
How many BTU it will need? Would an increase to R60 roof help?
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Replies
Pete,
Here are links to two articles which will give you guidance on performing a heat loss calculation:
How to Perform a Heat-Loss Calculation — Part 1
How to Perform a Heat-Loss Calculation — Part 2
Cooling load calculations are more complicated, and are best performed with software. For more information, see Calculating Cooling Loads.
For accurate calculations, you need to supply more information on several topics, including:
1. Concrete slab insulation details
2. Window areas
3. Window orientation
4. Window glazing specifications
5. Number and sizes of doors
Q. "Would an increase from R-40 to R-60 roof help?"
A. In all cases, increasing the roof insulation from R-40 to R-60 will lower the heating load and the cooling load.
Additional questions:
1. Tolerable temperature ranges in a warehouse can be different from those in an office or residence. I don't mean to discount the comfort of the workers in the warehouse, but in some scenarios they visit for 15 minutes once a week and 90-100 F at low humidity would be quite tolerable, if the goods in the warehouse are OK with that.
2. In a desert, the day-night swing can be large, so the average temperature is often much less than the daytime peak. If the tolerable temperature range is large, and/or you have substantial thermal mass (which could be the slab or the goods stored in the warehouse) you can overcool at night and ride through the daytime peaks without the need for as much cooling capability. Overcooling might mean down to 80 F if 90F is the limit during the day, to 72 if 72 to 80 is the tolerable range, or even to lower temperatures if you can take advantage of cheap electric rates at night.
3. I assume that since it's a desert humidity is low already so controlling humidity in the warehouse is not a concern, but if this were in a humid location you'd also want to consider what the allowable humidity range is.