Ventilation can either be done passively through openings or mechanically with fans. Roll up sides are an economical way of getting lots of air movement since no electricity is required. Roll up sides become even more effective when used on longer buildings. Roll up sidewalls are often used in combination with a small exhaust fan for early and late season ventilation when opening the sides is not practical.
If a structure is very exposed, it is best not to open more then 3’ in height due to potential of wind damage. If a structure is extremely sheltered, it is best to go even up to 6’ to create maximum opening. Roll up sidewalls are most effective when used in combination with peak end wall vents to create a “chimney effect” to draw warm air out of the building, especially when it is very calm. These vents are effective for air movement when outside temperature does not allow opening of the sides.
When a structure has a low profile, you will need to be careful during rainy periods due to moisture getting into the structure area. High profile structures (with straighter walls) usually work better with roll up sidewalls. When preventing a floor draft is an issue, the roll up mechanism can be raised and then the structure is lined with a skirt for the bottom 2’-3’. When using this method of ventilation, it should always be done on both sides. An effective use of this method includes opening the “downwind side totally and the opposite side on marginally.
We have previously covered the idea that while considering your structure choices you will have to weigh cost versus benefit or return. There is no area which this is more true then with cover choices.
The wide range of cover choices include glass, polycarbonate, polyethylene and woven products. Within each of these products there is an equally great variety of choices. Along with each of these choices there is a huge variation in cost and function or performance.
At Multi Shelter Solutions we manufacture a wide range of shapes and sizes of predominantly plastic and tarp covered buildings. Because these buildings and shelters are narrower and have a reduced hoop spacing, we can use a lighter cover of the options available. The easiest way to get a comparative cost is to take the replacement cover cost divided by the years of expected life span to get an annual cover cost.
Our 7.2 mil plastic covers can be used as a single layer or double with air between for a 30% reduction in heat loss and to minimize condensation. White plastic has a 4 year warranty against deterioration by the sun, clear has a 5 year warranty. Plastic is available in clear (greenhouses) and white (livestock shelters) and comes in various thicknesses. The average life span is 5 – 6 years for single layer and 6 – 8 years for double although 10 years is not uncommon.
Our 12mil white woven covers have a much greater tear resistance then plastic. This makes a good alternative when there will be some contact between product and cover. By providing shade, the white tarp is cooler in the summer. By still letting light in, it is warmer in the winter. Typical life span is 10 year.
You can see more info on these choices on our covering page or with the presentation video and the rest of the series Norm spoke on Greenhouses 101 here. As always, we are happy to help you with any of your questions regarding planning or options as you are considering your structure purchase.
The location and orientation of a structure are two different things that need to be given careful thought to since the consequences are so long lasting. The cost of making changes after the fact are significant and often make it impossible. You should never put a structure somewhere simply because the area is not good for anything else. Location is more about what you need and orientation has to do with what the structure needs to perform well.
Location has to do with accessibility to power, water and handling the product that the structure shelters. If bringing in water, electricity or a driveway is too costly for the budget at present, you will have to start weighing cost versus benefit. This can only be accurately done if you understand the requirements, choices and consequences. Drainage, ventilation and light requirements are also important considerations which change from location to location.
Orientation has to do with a structure being north/south, east/west, or somewhere in between. This will have an impact on ventilation, light, snow shedding and lay of the land. For all of these things you need to have a good handle on what the structure needs to perform well. A structure must be level from side to side to shed snow well but can have some slope from end to end. Ventilation is easier when a structure is inline with the prevailing winds but you do get more sunshine in the building if it is north/south.
Check out the presentation video and the rest of the series Norm spoke on Greenhouses 101 here. Stay tuned for the end of January 2016 when he presents Greenhouses 202!