Aug. 26, 2010

Big Belly

Crews spent much of the summer disassembling the old horticulture greenhouses so the components could be recycled or reused. Photo by Bob Elbert.

Horticulture greenhouses: Green even in demolition

by Anne Krapfl

Work to demolish approximately 27,000 square feet of antiquated greenhouses used by the horticulture department began in June and was completed in early August. Most of the old facility dated back to 1913; an addition was completed in 1980 but that also was outdated. Foundation work has begun on the approximately 13,500 square feet of state-of-the-art greenhouses that will replace them.

More information

Construction site webcam

Contact: Jeff Iles, chair, horticulture department

Re-use, recycle

Prior to demolition, any unclaimed plants from the old greenhouses were offered to ISU partners, including Reiman Gardens and Master Gardeners; other public botanical facilities; and the public. Unclaimed plants and those too large to move were sent to the university compost facility.

All salvageable materials and equipment were removed from the greenhouses. For example, the work benches will be reused either in the new horticulture greenhouses or other ISU greenhouses. Equipment such as fans, grow lights and vent motors were salvaged and will be reused in the new greenhouses or kept for replacement in other ISU greenhouses.

All of the greenhouse glass had asbestos glazing, so the glass and glazing had to be removed and disposed of as hazardous material. Nearly 30 tons of steel and aluminum structural material, miscellaneous metals and wire were salvaged for recycling. The concrete floor was separated from rebar, with the concrete going to a local stockpile for future crushing and reuse and the rebar being recycled. After all these salvage and recycling efforts, the materials taken to the landfill amounted to little more than a dumpster.

A team evaluated the 1980 greenhouse to determine if it could be upgraded or moved to another location and reused. The glazing in this greenhouse also contained asbestos, and the cost to abate the asbestos and dismantle and reassemble the greenhouse was double the cost of a new greenhouse. So it became part of the recycling project as well.

What is state-of-the-art in 2010?

The new greenhouse, expected to be completed next spring, will have hot water in-floor and perimeter heating, evaporative cooling, shade curtains for energy conservation and light control, and a computer control system that automatically will control all aspects of the greenhouse. Energy-efficient features will include grow lights controlled by the plants' needs based on solar conditions, efficient in-floor heating and automated ventilation and lighting that responds to plant needs but conserves energy. These systems will allow year-round use (not possible in the former greenhouses).

Individual greenhouse rooms are designed to maximize floor space with rolling work benches. So, even though they'll be half the size of the former greenhouses, the new ones will support the activities of the horticulture department.

What's next

Footings and concrete work for the new greenhouses has begun. The new greenhouses will arrive in October and will be erected by the end of the calendar year. Interior work will continue through the winter and spring.

In the meantime, the department has no greenhouse space. Researchers have found space elsewhere or are limited to refrigerator-sized growth chambers in Horticulture Hall. Greenhouse-reliant courses, many of which are offered every other year, are on hiatus until next fall.