The Problems - General:

•	Heat
•	Lack of air movement
•	Tobacco smoke
•	Condensation
•	Body odours

The Problems - Shop Windows:

•	Heat
•	Condensation
•	Deterioration of stock

Solutions:

SHOPS/STORES - Air change rate per hour 8 minimum

The wide variation in size and particular purpose of these buildings makes very little difference to the basic method treatment: namely, extract at high level and draught-free air replacement at low or medium level, speed control being essential.

The air flow through the premises can be from front to back, or back to front if the traffic fumes from the front are a nuisance; or from low level to ceiling or roof. A comparatively small shop with no outlet at the rear, can be dealt with by extracting at one side of the front of the premises and intaking at the other side, both at high level. Alternatively, if the shop is more than 9 metres long, the best results are obtained by fitting a duct from the front intake point to the rear of the shop, with suitable grille(s).In this way, the fresh air is delivered to the back of the shop, which normally needs more air movement. It is then drawn forward to the extract point, thus 'sweeping' the space with cooler, fresher air.

Larger shops and supermarkets usually can be dealt with by using a simple arrangement of extract units at high level in walls or roof. Air replacement is via open doors and/or intake units.

SPECIFIC PROBLEM AREAS e.g. Lighting and refrigerators
In some premises, discomfort can be caused by heat build up from intense lighting and warm air discharged into the shop from refrigerated cabinets. In such cases, 15 air changes per hour or more may well be necessary, together with 24 hours thermostatic control.

DISPLAY WINDOWS
Adequate ventilation of the shop itself will in may cases be all that is necessary to control window condensation. Where a condensation problem exists which is limited to the display space only, specific ventilation will be required, possibly to a rate of up to 15 air changes per hour. Heat gain from lighting can also cause drying out and discolouration of stock. Use one 230mm extract unit for every 2kW of lighting. (1kW in difficult cases). Condensation should always be extracted to atmosphere, with air filtered replacement from atmosphere at low level. For heat problems, air replacement may be taken from the shop or atmosphere at low level, with discharge to atmosphere or back into the shop during colder periods.

SIZE AND NUMBER OF VENT-AXIA UNITS
Calculate the volume of the room (height × width × length) and multiply by ACH. This equals the volume required per hour. For display windows see text. Choose the size and number of units from the output table to ensure that this minimum volume is achieved. Controllers can be used to boost the output of the units during warmer spells. Ensure that the scheme complies with relevant local authority by-laws and fire regulations.

Axial fans Output Range 150 mm ø 225 - 285 m³/h 190 mm ø 325 - 425 m³/h 230 mm ø 510 - 710 m³/h 300 mm ø 1190 - 1560 m³/h