HVAC AND IAQ SYSTEMS

• By Thomas G. Dolan
• 01/01/08

When shopping for HVAC and IAQ systems for your school, it might be easy to assume that all that’s involved is finding the latest and greatest — at the best possible price. But much more is involved than simply purchasing and installing the mechanics and ductwork. Considerable preplanning is necessary to make sure these systems work effectively.

Here are the recommendations from two sources who are know­ledgeable about this process. The first is Larry Wei, product manager of the equipment manufacturer, Lennox International Inc., Richardson, TX; and the second Thomas Perry, managing director of engineering services for the construction management company, Shawmut Design And Construction, Boston, MA.

First of all, why is this issue so important?

“Certainly, in recent years there has been developing a real awareness that you have to match up systems that result in adequate indoor air quality because of the health impact,” says Perry. “There have been all kinds of studies that show that poor air quality directly contributes to flu, asthma, headaches, and other problems. You need air quality to create a better environment and better productivity. Kids spend 80 to 90 percent of their days indoors, especially at school. So you want to design a system that fosters but does not inhibit indoor air quality.”

Wei agrees. “Before you install your mechanical equipment, your biggest concern should be the health of the students, teachers, and other occupants. Look for equipment that is designed to clean or improve air quality.”

A key criterion is choosing equipment with a good filtration system, one that takes the bad air out of the inside and brings fresh air in from the outside, Wei says. Good air from the outside should work in conjunction with highly efficient filters that are able to capture the contaminants from the inside, resulting from construction materials, furniture, cleaning chemicals, and, especially, people, who breathe out carbon dioxide which, in large quantities, can be harmful. “You want your filter system to capture even very small particles, such as bacteria,” says Wei.

The amount of outside ventilation, Wei continues, is dependent upon a number of factors, such as the size and type of the building, the number of occupants, as well as building codes — all of which are part of the preplanning.”

The placement of the ventilation from the outside is also important, says Wei. You don’t want the air intake too close to the exhausts, especially from areas such as the bathrooms and kitchen. Nor do you want it close to major roads, the garbage area, or parking lot where school buses will idle. “A lot of this is common sense,” Wei says. “But people don’t always apply it.”

You don’t want to turn on these systems either too early or too late. “It’s not recommended to use the HVAC systems when you have very high dust loads, such as while you’re drywalling,” says Wei. “Wait until all of the construction is finished and the interior cleaned before you turn the systems on.” On the other hand, he adds, it’s good to completely air out the building from the lacquer, glue, and other gases emitted from new building materials, carpets, and furniture before the occupants arrive.

“Another thing you can do from a preventive standpoint is control humidity, for excess humidity results in mold which causes a lot of asthma and throat problems,” Wei says. He refers to the ASHRA 62.1 standard which recommends that humidity should be kept below 65 degrees at all times.

There is a delicate balance between humidity and temperature control, Wei explains. In the past you would lower humidity by lowering the temperature. Lowering the temperature can lower the moisture, but it can also create moisture and the conditions for mold, especially in the air conditioning system. One solution is to have the removal of humidity not related to the temperature. The separate dehumidifier can be a part of the main system or stand-alone devoted just to that purpose. Also higher temperatures tend to generate bacteria growth, but these bacteria can be killed by ultra-violet lights.

“Temperature control is very important for good student productivity,” says Perry. “Shawmut has about 900 employees, and one of my tasks is teaching employees on these issues. I’ve personally noticed that when the temperatures are not right, attention flags and learning is inhibited.” On the one hand, if the classroom is cold and drafty, especially around the perimeters, this can adversely affect learning. On the other hand, too high a temperature can create discomfort. Many of these issues should be addressed in the design of the building envelope, he suggests. In fact, these matters should be considered even at the time of site selection.

Another key preplanning issue, which goes hand-in-hand with creating a conducive learning environment, is energy efficiency. “The HVAC system is one of the big energy users in the building,” Perry says. “So you want to consider the operational costs. There is a trend, not just an awareness, but an acceptance that going green is a way not only to enhance learning, but also to cut operational costs.”

Perry maintains that simply designing a code-compliant or conventional building is not very cost effective over the long run. “If you can get a green design, even though it might cost one to two percent more initially, you can save 30 to 40 percent in energy costs. Over a 20-year period, that can add up.”

There are many ways to do this, he explains. One is through geothermal or ground heating. Basically, the earth is used as a heat source. This can greatly reduce the use of thermal fuels on site. “If your school has a lot of cooling demands, this is a good candidate,” Perry says. “With green design you can also use waste water on site, and save an average of 30 percent on your water bill. But all of this should be considered in the planning stage. You have to consider all options, then forecast the installation costs and energy benefits. Design and construction teams should work together. It’s not enough for someone just to toss a design on the table and say that’s it.”

Ideally, all of this would take place in the planning for new schools. But, realistically, there are a lot of older schools out there that have a lot of problems with poor air quality and inefficient energy systems. Can these same principles be applied to renovation?

“We do a fair amount of renovation projects,” Perry responds. “The same dynamics come into play, but instead of just putting together the construction manager, designer, and architect, include the key school administrators and personnel who are responsible for creating a good environment.”

Another element of preplanning, which Perry says is often overlooked, is building into the procedure a post-occupancy testing program of at least once a year. “The system needs to be reviewed every year to fine tune it and make sure that everything is still in sync and hasn’t fallen out of calibration,” he says.

Where did this concern for student health and green buildings come from?

“In the late ‘70s and ‘80s there were many sick buildings due to the building materials and lack of ventilation,” Perry responds. “The general awareness has been gradually growing, but over the last couple years the awareness end implementation of good measures have increased considerably.” Perry mentions studies and recommendations growing out of organizations as diverse as the American Federation of Teaching, American Lung Association, U.S. Green Building Council, American Institute of Architects, Federation of American Scientists, and so on.

When asked where schools are in terms of their becoming a part of this trend, Perry replies, “I think schools have really picked up on this. They understand the benefits. Every time I go to a conference the buzz is all about green buildings. Walk into any college and it’s likely they will have sustainability initiatives. About 90 percent of them do. It’s also trickling down to K-12. They may not have sustainability managers. But they want to go green. Green has  become a catchphrase, both nationally and globally. Everyone hears it so much. Those influential on school boards are demanding it. And sometimes going green can generate funding, from both public and private sources. We’re seeing this happen on occasion.”

Perry closes by saying, “The way I look at it, those from the outside may be involved in a building project for a year, but the owner is going to have it for 20 to 25 years. You need their input. You want to match up the HVAC controls with the abilities of those running the facility. You want to make sure the controls are not too sophisticated or simple. It’s all a part of the preplanning.