CREATING OPPORTUNITIES

Menkes Developments Inc. developed four office buildings in Mississauga and Richmond Hill, Ontario. Each building is four stories high with 25,000 sq ft of space on each floor.

Xtra Mechanical Ltd. was hired to install the heating and air conditioning system for each of the structures. The companies wanted to do something unique that would help their client save valuable office space, as well as save financially. Menkes and the mechanical contractor teamed up with Nexsus Engineering Group Inc. and Lennox to engineer such a system.

The team decided to use the L-Zone, which uses L Series rooftop units with zone dampers in the air ducts. They chose to use rooftop units in conjunction with the zoning system, as opposed to a variable air volume (vav) system, to save office space. A vav system would require a mechanical room on each floor, which would have reduced the amount of available space.

Greg Winterhelt, Lennox controls specialist, says that the zoning system used a direct digital control (ddc) system and was able to link multiple rooftop units and zone dampers. Each zone damper was connected to a room sensor so that each office has its own thermostat.

NOT-SO-LARGE COMMERCIAL

It is not unusual that the application used rooftop units with the zoning system, but it is interesting that rooftop units were used on a four-story building.

According to contractor Dave Irwin, president of Xtra Mechanical, the manufacturer was chosen in part because it makes a 30-ton rooftop package unit. This size allowed the company to use rooftop units on a smaller-sized office building.

Andy Kostopoulos, account executive for Xtra Mechanical, says that using rooftop units with the zoning system allowed for easier installation and future serviceability. For one thing, service technicians do not have to be in the way of office employees when work needs to be done on the system.

For the first building, one 5-ton unit and eight 30-ton rooftop units were used with an L-Zone monitoring system.

Zone dampers with demand flow control are monitored from more than 100 different control panels throughout the building. Each floor of the building has its own panel, which can be a benefit in buildings with multiple tenants. The control panel can also be used to wire in other services, such as lighting and security.

Xtra Mechanical also installed an energy recovery ventilator (ERV) and CO2 sensors along with the zoning system. Lennox says that the ERV equalized pressure from heated indoor air out of parts of the building and brought fresh air back in. The CO2 sensors also controlled the amount of fresh air brought into the building based on demand instead of fixed flow. This, according to Lennox, helped save more energy.

“We are able to offer the end user a product that would classify the building as high end, but we saved a lot of money with the packaged units,” said Ennamorato. “Now the builder can offer tenants more useable area and lower rent because of the money saved with the hvac system.”

The first installation was such a success, Xtra Mechanical and Menkes decided to copy almost the exact installation procedure with the next three buildings.

Lennox says it has been involved with a number of commercial zoning projects in Canada and the United States. Many of the more recent projects use the manufacturer’s Sectra commercial zoning system.

ZONING IMPROVEMENTS

The Sectra system is similar to the L-Zone. It offers the same benefits and helps relieve temperature and air quality differences in commercial structures. However, as many as 18 rooftop units can be used to control up to 100 zones by using the Sectra.

The system also has fully modulating airflow dampers to control the airflow to each zone, which can ensure true vav control, the company says.

The manufacturer says control points in each zone sense the temperature and air quality, and open or close dampers or activate reheat elements to allow a precise level of conditioned air into the room.

One of the primary benefits of zoning systems is that they can save energy and energy costs by providing conditioned air only to selected areas. The Sectra can take this one step further by allowing a single thermostat to control multiple zones.

Also, according to Winterhelt, the Sectra uses LonWorks technology, so different manufacturer’s components can be used in conjunction with the zoning system. It can work with a number of other applications as well, such as indoor air quality (IAQ), CO2 measurement, and control of lights/security.

Another added feature is the ability to perform remote monitoring of the zoning system. Winterhelt explains that the Sectra has a modem dial. This allows building owners to check on the performance of the system, and it allows contractors to check on possible system problems without having to visit the site.

Publication date: 05/27/2002