All across the world, Ceres has helped growers create sustainable, energy-efficient commercial greenhouses in a wide range of climates. While you can’t choose your climate, many commercial greenhouse growers have options when it comes to location and orientation of their greenhouse. Several factors go into a good greenhouse site: solar aspect, shading, zoning, wind, access to water, electricity, etc. The following tips provide a guide to choosing a commercial greenhouse site. If you have specific questions regarding commercial greenhouse siting please contact us.
Disqualifying Siting Factors
First, let’s start with site requirements that would disqualify a property from being eligible for greenhouse construction:
- Roads to the site are not wide and strong enough (incl. bridges) for heavy trucks transporting building materials.
- Not having appropriate power available or at least reasonably attainable – Ceres will provide information for your overall power needs (kVA). We will go into this topic more in-depth below.
- Not having access to an ample water supply. Water quality is not as important because it can be adjusted with treatment processes.
- There isn’t a reliable internet connection. Internet access is important for the functionality of the SunSense™ greenhouse controller. Satellite connection is sufficient.
If you’re weighing your options
There are factors that should help you lean one way or the other if considering more than one commercial greenhouse site:
- Shading / percentage of sunny hours at any time of the year. If you are choosing between two properties, you will want to contact Ceres to help you evaluate your options. Reviewing potential shading is super important and can vary significantly especially in mountainous and forested areas.
- The driving distance for employees to commute to the greenhouse site. If it is excessive (more than 1 hr), you will struggle maintaining growers and support staff. This is a major issue if you want to grow successfully.
- You should also consider how far away your greenhouse is from the market. It might be worth paying more for a property if it’s closer to your distributors, retail outlets or customers.
- The ground at the site is not flat. If there is more than 5 ft (1.5m) between any lengths or diagonals of the greenhouse, it will cost more money to excavate and level the greenhouse site. For a larger facility, ‘fixing’ a slope of 15 ft could cost upwards of $50/sqft.
- There are power lines going through the property that would affect your building height. If you aren’t able to move these lines, consider a different property.
- How windy the site is. Lots of wind at your site increases the cost of the structure (more steel) and potential creates more wear on your glazing.
- The site has a probability of being flooded. You will want to get an evaluation of whether or not the property is in a flood zone. Choose a property that will not easily be flooded.
- The property’s proximity to neighbors. If you are growing cannabis, odors can be a problem to nearby residents and heavy trucks may cause safety concerns. Know that odor issues can be avoided if you decide on a SunChamber™ because the sealed design will prevent inside air from escaping the facility.
- Bedrock depth. If the bedrock is close to the surface, burying geothermal systems, like The EcoLoop™ or GAHT® systems may be near impossible. Greenhouse projects integrated with EcoPack™ HVAC systems may not be affected.
- Water table depth. High water tables can cause problems while pouring the foundation and significantly increase concrete prices.
- Solar PV accessibility if you are interested in harnessing solar power for your greenhouse operation.
- If you are interested in installing solar panels, but want to be space-efficient on your primary licensed site, it may be advantageous to look for a greenhouse site that is surrounded by less expensive neighboring property to install your solar array next door. This will allow you to max out your primary property with greenhouse space.
- You may also consider a property with access to net metering. This means access to a system in which your solar panels are connected to a public utility power grid and surplus electricity is transferred onto the grid, allowing you to offset the cost of power drawn from the utility.
- The energy rebates available from the local power supplier. Some utility providers offer rebates, some don’t, so choosing a site serviced by a provider that offers rebates can save hundreds of thousands of dollars. Ceres can also help you manage the rebate and incentive process, with your local utility, to maximize your savings.
Siting factors that Ceres can design for
The following is a list of siting issues that can be overcome with help from the Ceres design and engineering team:
- Prevalence of large hail. How often and how big (relevant if over 3/4” or 2 cm)? This will significantly affect what glazing you choose. If you cannot find this information, Ceres can help.
- Prevalence of freezing rain. This can cause excessive roof loads and equipment failures. If freezing rain is an issue in your area, a Ceres engineer can factor this into your roof loads and equipment specification.
- The frequency and longevity of power outages in your area. If they happen often, how long do they last?
- If power outages usually only last a few hours in your area, Ceres can easily configure them into your engineering.
- If outages can last up to a day or more, your site may require backup power generation
- For outages lasting up to a week or more, you will need significant backup equipment (full backup power) that can add significantly to the overall capital expenditure.
- Your local agricultural wastewater regulations. Waste water can be cleaned before it is released but this process can be expensive to purchase and operate.
- Proximity of the closest CO2, fertilizer, and propane suppliers (if applicable). If the distance is too far, supplies can be expensive and/or unreliable to transport, especially in cold/snowy winter locations.
- Water running through any part of the building site. Can the water be diverted to other more favorable locations? Can the water be collected? This can potentially be a very expensive site preparation and cause danger in flooding events.
- Seismic restrictions on the property. High seismic loads mean higher structural and engineering costs. In certain areas, seismic loads can vary within one section of road. It is important to know the seismic loads of the property itself.
- The presence of a natural gas connection. If you don’t have a natural gas connection, we have design and engineering solutions for you. Our SunChamber™ facilities can run 100% on electricity.
Now let’s get into more detail about some of the more important siting factors:
Evaluate Light by Season
Building orientation is probably the most significant siting factor, particularly if growing year-round in an energy-efficient greenhouse. If located in climates with moderate to harsh winters, appropriate solar exposure is essential for sufficient growth and passive solar heating. If the site is shaded in the winter, it can result in lost production or more expensive lighting bills. In contrast, in the summer some shading is usually inconsequential and even benefits the greenhouse by reducing summer heat gain, preventing overheating depending on the cultivar. Many growers simply turn to shade cloth and cooling strategies to help keep the greenhouse cool in the summer.
There are several ways to evaluate light levels at your site. Maps and weather sites like NREL can give you an idea of total light levels in your region. From there you can get more site specific, evaluating anything that can shade the greenhouse (called obstructions) such as buildings or nearby trees. If there are nearby obstructions, we recommend predicting their effect on the greenhouse. Several methods can do this such as using trigonometry and a sketch of surrounding objects. A tool called a Solar Pathfinder is another possibility, as is having a greenhouse designer or engineer model your site and predict shadows – one of the many greenhouse consulting services we offer at Ceres.
Below is an example of a shade analysis for a Ceres HighYield™ Kit greenhouse in the winter and summer. This design software allows us to use a simulation to identify the best positioning and orientation for your greenhouse, taking into account all the nearby possible obstructions.
Light meters are another option, but usually challenging to give a full picture of light levels throughout the year. With a light meter you are directly measuring real-time light levels. They only measure light intensity, or light levels at a single point in time. That requires a data logger or taking several readings to get a full picture of light at your site, since daily shifts in light can be huge. These devices range from cheap and simple, to advanced and very expensive.
Get to know permit stakeholders
Zoning regulations are an obvious factor in choosing a site. Typically, a commercial greenhouse site must be zoned commercial or as agricultural land. In urban areas, there may be some added flexibility for zones, as many cities are amending laws to encourage small-scale urban farms. (The Sustainable Cities Institute has a good list of urban farming amendments, many of which apply to commercial greenhouses as well as outdoor urban farms and gardens.) Urban sites often come with added regulation, though, when it comes to the planning and design of the project.
After you identify that a site will allow a commercial greenhouse, we recommend speaking directly with key stakeholders when applying for a building permit. Talking to regulators– whether zoning commissioners, a land use department, or building department – can help identify their key concerns and how to answer their questions. Keep in mind that many key stakeholders – permit officials for example – may be unfamiliar with commercial greenhouses. At Ceres, we commonly see initial concerns regarding energy usage, durability, and quality of materials… all of which can be assuaged with some education on how our greenhouses are built. For example, commissioners are often surprised to know that commercial greenhouses can be energy-efficient. Addressing these concerns early on helps streamline the permitting process.
Ensure water and electricity availability
Both are essential to energy-efficient commercial greenhouses, or any commercial structure for that matter. We recommend speaking directly to your local utility about electric hook-up when evaluating a site, if it is not already there. This can be an expensive recourse if the utility is not willing to pay for it. It involves bringing out electric lines to the site. Determining what voltages are needed is also key to the planning stage. Most commercial greenhouses require 480V 3 phase power, which isn’t available at all sites and can be expensive to bring to a site where it isn’t already available.
Even if grid-power is accessible, many growers add solar panels for other reasons. Combined with passive solar greenhouse design, solar panels can create a net-zero energy commercial greenhouse that reduces operational costs and promotes a business’ environmental commitments. It’s important to realize, though, that they also dramatically influence the budget (though financing is possible).
Evaluate proximity to market
How close are you to your customers, retail outlets or distributors? This is often less of a crucial factor for many large-scale operations. It does come into consideration for smaller commercial growers who may be selling direct to the end user (e.g. farmers markets or CSAs) or to a few retailers / restaurants. For example, a client recently approached us about building a large-scale commercial cannabis greenhouse in Washington. Due to regulations on the crop, they could only sell directly to retailers, requiring a complicated delivery chain. Their choices were to locate a greenhouse in a more urban area, closer to retailers, or locate the greenhouse further away. While the urban site was a more expensive build out, the savings from avoided transportation justified the additional upfront cost.
The availability of local labor should also be considered, as it’s important for employee success and retention.
For most commercial greenhouses, distribution is not a make or break factor in a site, but should be anticipated when planning the business. How much this plays into your siting decision a factor depends on your marketing and distribution strategy, which varies by operation.
Avoid windy sites
An ideal greenhouse site is protected from strong winds. Winds increase wear and tear on the structure, adding maintenance or possibly reducing its lifetime. Vents are particularly susceptible to the ‘sail effect’ — being torn off in strong gusts.
Winds also increase the structural loads on the greenhouse frame, mandating stronger roof framing. This in turn can add to cost if wind loads are significant. For example, Ceres designed and built a commercial cannabis greenhouse in Leadville, Colorado – a site with 120 mph gusts. The structure required heavy gauge steel I-beams rated for the high wind loads. A super energy-efficient greenhouse in the end, the wind loads were a major factor in the commercial greenhouse design and engineering.
A final deterrent is that winds ultimately increase the rate of heat loss through a year-round greenhouse. They both add to air infiltration (cold air blowing into the structure) and create pressure differentials around the building. Differences in pressure in turn increase air movement, making a year-round greenhouse less energy-efficient in the winter.
Often, winds are simply a fact of life for a commercial greenhouse site. Regardless of the weather in your area, Ceres will engineer your greenhouse structure to your local wind loads.
For more information, or to speak to a greenhouse expert about your commercial greenhouse project, contact us today!