Tuesday, May 17, 2011

Observations of a Canadian LEED Certified Building

While I was in Canada a couple weeks ago, I was given a tour of an almost completed Quebec Government building. The building was an extension of a combined train station / administrative office complex. The addition was the equivalent of the Department of Transportation in the US (I have no idea how to translate that into French).

Language barriers aside, our tour guide was a manufacturer’s rep who had sold all of the air distribution in the new addition. We even got to meet the lead design engineer, as the building was going through the commissioning process, and he was overseeing that process. I was impressed with several things in the new building:

1) The addition was a very fast track construction project, completed in what may be record time, with 6 floors of offices and a parking garage. People were working in the building before it had been commissioned!

2) The open plan office had no closed offices at the perimeter, all conference rooms and executive offices were located in the core, resulting in excellent visibility.

3) There were no desks against the windows, and the spaces near the windows were all corridors.
Partitions were low height, except for some separating operational areas, and these 6ft partitions were all perpendicular to the window wall, allowing excellent daylighting into the interior.

4) The south facing wall had exterior shading and an interior light shelf (with a gap to allow airflow down the windows), again to increase daylighting into the interior.

5) The HVAC system was ECM powered fan coils with VAV boxes controlling ventilation air into the fan coils. The lead engineer said the result was less than 1Watt/SF load, and there were no true air handlers, only DOAS units bringing in and conditioning outside air.

6) The zone air distribution was European style fully adjustable radial pattern 2x2 fixtures with 2’cube plenum boxes on top. These constant volume air devices have very high induction and resultant short throws, and appear to minimize jet collision and resultant downdrafts. Air flow rates were relatively low, less than 1cfm/sf in interior zones.

There were also some issues:

1) It was also reported that the combination of ECM motors and digital lighting ballasts resulted in a building power factor of 0.85! As there is a power station in the basement, power was re-conditioned on site.

2) The air outlets have relatively high pressure drop (0.5”) and are at least 5x the cost of typical office diffusers in the US. This cost is typical in Europe, but would be considered prohibitive in most US designs. There is little data on the performance of this style of diffuser in terms that are comparable to US designs; nevertheless, we will be testing a unit to get comparable performance data.

Authored by: Dan Int-Hout, Chief Engineer Krueger