NGMA Saves Your Glazing

Chris Beytes

Not to overstate the situation, but if the National Greenhouse Manufacturer’s Association hadn't been monitoring the International Code Council (ICC) actions, you might have found your glass or polycarbonate greenhouse in violation of new energy codes. You’d have had to install double poly AND an energy curtain to make it legal in areas that follow International Energy Code (IEC) guidelines.

To backtrack a bit, in recent years, NGMA has represented our industry on several building and energy code issues. For instance, in 2018, NGMA was able to get greenhouses coverings exempted from the energy code. This allows you, the greenhouse owner, to choose the glazing that’s appropriate for your crop and climate, not some code official who doesn’t know a greenhouse from the White House.

However, in April, the topic came up again thanks to public comment. A new IEC proposal would have required non-opaque greenhouse coverings to meet a minimum U (thermal transmittance) value of 0.7 BTU/hr. per sq. ft. That’s equivalent to what a double poly roof offers, and would basically have outlawed glass, polycarbonate (even twin-wall) and single poly on any commercial greenhouse where the IEC is enforced. And the rule wouldn’t have taken into account geography, energy use or the type of crop grown.

“While the NGMA is big on energy conservation and building greenhouses that lower growers’ utility bills, this proposal reaches too far and creates too many unintended consequences for ornamental and vegetable growers,” said Matt Stuppy of greenhouse manufacturer Stuppy Inc., and a member of NGMA’s Codes and Standards committee.

Thankfully, Matt and fellow NGMA member Paul Jacobson of covering and screen manufacturer Green-tek Inc. were on hand at the International Code Council hearing in Las Vegas in late October to publicly comment and fight to keep the greenhouse exemption and were victorious.

For now, that is. There seems to be increasing attention on greenhouses among code authorities, municipalities and other interested parties, especially as cannabis greenhouses become more widespread and come under tighter scrutiny.

“This will continue to be an issue for the industry and I would expect pressure from energy conservationists to increase,” Matt told me via email, after the favorable ruling. “Our industry needs to do a better job of educating the building construction industry on the benefits of greenhouses and how greenhouse growers are more energy-efficient than ever.”

Thankfully, NGMA recognizes this and will continue to keep a close eye on the ICC for more proposals that could impact your ability to grow plants cost-effectively. GT