Supermarket heat load calculation

[nike123]

How to calculate air change heat loss thru doors of supermarket.
It has two doors which are frequently open by motion detector of these dimensions: 3mx2,2m

My taught is to calculate only required air changes by space and make supply ventilation flow slightly higher than discharge air flow to make space in slight overpressure and heat loss thru the doors would then be only difference in air flow between supply and discharge air. And maybe to install air curtains at doors to decrease losses.
Also, Heat recovery coil would be mounted in supply/discharge ventilation.

Am I right, or I have something wrong?

[Brian_UK]

Nope, I think that you have covered it.

[nike123]

Nope, I think that you have covered it.


Thanks Brian!

[Greengrocer]

Hi Nike. Do I take it you have some exhaust air as well as return, supply and fresh air? If so what are the percentages? Also is their any free cooling - I assume we are talking about A/C here and not a cold room.
Normal procedure is to slighly over pressurize the conditioned area to avoid untreated outside air coming in through opening doors etc. Fresh air comes into system via the AHU (perhaps with pre-heat in winter), mixed with % of return air and treated via main cooling / heating coils.
A door curtain would be a good idea to prevent wind assisted ingress and to minimise conditioned air loss. Electric heater may be needed for winter operation. Alternatively Mitsubishi now offer a Heat Pump heating only Air curtain system. Quite expensive compared to an electic heater curtain but will save a lot of money in running costs. Details are on the UK Mitsi web site under Products, Mr.Slim, Air curtain - its a downloadable PDF. Daikin also do one now but their's can only be connected to a VRV system. Mitsi's is a 1:1 split system.

[chinatim]

How to calculate air change heat loss thru doors of supermarket.
It has two doors which are frequently open by motion detector of these dimensions: 3mx2,2m

My taught is to calculate only required air changes by space and make supply ventilation flow slightly higher than discharge air flow to make space in slight overpressure and heat loss thru the doors would then be only difference in air flow between supply and discharge air. And maybe to install air curtains at doors to decrease losses.
Also, Heat recovery coil would be mounted in supply/discharge ventilation.

Am I right, or I have something wrong?
me doing the similiar as you, however i also test if the ventilator flow then decided the plan.

[nike123]

Hi Nike. Do I take it you have some exhaust air as well as return, supply and fresh air? If so what are the percentages? Also is their any free cooling - I assume we are talking about A/C here and not a cold room.
Normal procedure is to slighly over pressurize the conditioned area to avoid untreated outside air coming in through opening doors etc. Fresh air comes into system via the AHU (perhaps with pre-heat in winter), mixed with % of return air and treated via main cooling / heating coils.
A door curtain would be a good idea to prevent wind assisted ingress and to minimise conditioned air loss. Electric heater may be needed for winter operation. Alternatively Mitsubishi now offer a Heat Pump heating only Air curtain system. Quite expensive compared to an electic heater curtain but will save a lot of money in running costs. Details are on the UK Mitsi web site under Products, Mr.Slim, Air curtain - its a downloadable PDF. Daikin also do one now but their's can only be connected to a VRV system. Mitsi's is a 1:1 split system.


The space is medium size (360m^2). It is for space cooling. Percentages I don't know since that is not my project, it is principle discussion with my colleague on local newsgroup.
It will have fresh air supply and exhaust air on heat recovery coil, and I suppose, fresh supply air after passed recuperation will be additionally conditioned with split system air conditioner duct fan coil.
Space will be heated/cooled with split-system air conditioners which only works on indoor air recirculation.
Door air curtain will probably have electric heaters for heating season
VRV systems are to expensive here for our average businessmen, since our society is in "primitive accumulation of capital" (http://en.wikipedia.org/wiki/Primitive_accumulation_of_capital) phase after change of our economic system !

[nike123]

me doing the similiar as you, however i also test if the ventilator flow then decided the plan.

I am afraid that I don't understand your point.