Heat load calculation

Question

100sqm area required temperature 23c

outsaid Th 30c

Answer 1

This should help. You will have to convert from and to metric.

You can download convert for windows too.

Answer 2

a contractor will use a rule of thumb calculation, a/c 30 btu/hr per sqft where 1 ton a/c is 1200 btu/hr. for heating 1 watt per sqft. this rule of thumb is accurate only to a small house. when the a/c being questioned the contractor come up with a little more accurate estimate as follows

cat#1 poorly insulated house - 90 to 110 btu/hr per sqft cat#3 normal insulated - 29 to 35 btu/hr per sqft, cat#5 very well insulated house - 10 to 13 btu/hr per sqft

above numbers are used to multiply the square footage of the house assuming 10ft ceiling. and come up with heating or cooling requirement for the house.

still its not accurate because heat loss is related to surface areas of the house not the cubic volume, but the contractor will not spent hours to calculate heat loss based on the house surface areas

the actual heat loss calculation can be programmed in the computer base on

Q = (A)(To - T1) / (R)

Q = heat loss Btu/hr

A = surface area sqft which involved ceiling, front and back exterior wall, and left and right side exterior wall, floor surface area of the room above the  unheated garage.

To = outdoor temp F (86F)

Ti = indoor tem F (73F)

R = R value of insulation

above formula is using us imperial units, for the international SI units

Q = watts

A = sq.m

T = in kelvin

R = in RSI

example

window single glass R value is 0.91, poured concrete 8" R value is 1.11, fiberglass 3.5" in a 2"x4" stud has R value of 10.

some country has the following rules

for the wall use R-27 (wall shall be insulated R value of 27)

ceiling use R-40 (ceiling insulated with R value of 40)

the conversion, in us imperial system when called for R-10, it is equivalent to SI international system of RSI-1.761