There are basically two choices for ventilation. With NATURAL ventilation a system is installed where the laws of nature take over to cool the building or environment you have. With FORCED ventilation a mechanical system is installed to control both the quantity and timing of the air movement. Both methods have numerous variations and there is a direct correlation between the operation and installation cost and the effectiveness and control possible.

The following is a summary of some of the choices you have with some of the advantages and disadvantages of each. There are too many variables to list here. Do not hesitate to call to clear up any confusion or to ensure you get the right system for the function you wish to acheive

• Natural ventilation through doors and windows is the simplest method since these are usually part of the end wall construction. The major disadvantage is in the control since you have to be there to open and close. The effectiveness is greatly reduced if the structure is not in line with the prevailing wind. Using triangular vents or doors high up on the gable end improves the performance since this is where the heat is.
• Using roll-up side walls is much more effective since the opening to airflow is much larger. The basic installation cost is very low ($2 - $3 per running foot x 2 sides) with some upgrades as in using alternatives to wood in the cover fastening. The biggest disadvantage still is that you have to be there to open and close the sides. The operation cost therefore is tied to what you figure your time is worth. There are some methods of motorizing this system but it usually defeats the purpose which is low cost. The manual system of roll-up side walls is included where ever there is reference on this web site to “package price” It is usually quite simple to install this after the fact or to other types of structures.
• Using a roof vent is very effective since it is located where most of the heat is… at the peak. The cost for installation is quite a bit higher ($17 - $20 per running foot). Installation of the cover is significantly more awkward since there needs to be a split at the base of the vent. Adding a chain driven gear box does not add significantly to the cost but does still require an operator. Adding a motorized gear box and controller can cost up to $2000 but does allow you to fine tune the temperature control.. This system is usually only practical on long structures where the investment is spread out over more square feet.
• Forced ventilation always involves a motor driven exhaust fan. The fact that there are so many sizes to choose from allows a huge range of flexibility and at the same time can cause a problem when the fan(s) are sized and placed wrong. All fans have a c.f.m. rating which indicates how much air they are capable of moving. To get the air volume of the building multiply width by length by height and then determine what you optimum minutes per air change is (or air changes per minute). One fan is usually cheaper while 2 fans can give a more balanced air flow.
• Proper air intake is part of a forced ventilation system. Using motorized aluminum louvres will allow you to add the air intake to the thermostats which control the exhaust fans. Where ever possible you should avoid putting air intake on the west or south facing walls since this will allow much warmer replacement air to come into you building