Ask the Expert July: Eric Van Benschoten, CEO of Van-Fort discusses building commissioning and underfloor ventilation

As he prepares to entire retirement, we spoke to Eric Van Benschoten, CEO of Van-Fort, about what he's learned in his 40-year career in the building industry. In particular, the projects that stand out for him, his impressions of underfloor ventilation, and what he's learned about improving the process and timelines of green projects.

1. Tell us about your background and how you got involved in green building.

Canadian War Museum, Ottawa, Ontario

As a building science graduate and working in construction over 40 years, I found the industry could be doing better for energy conservation, and much of this is due to the need for a holistic approach to the construction process.

Having worked on industrial projects and with process equipment, there appeared to be too much being missed on commercial and institutional work near the end of a project in order to meet the "on time and on budget" mandate, that resulted in clients spending years sorting out problems. Often the client did not even understand the design intent when dealing with building issues. For this reason and with the recommendation of LEED accredited friends who were doing building energy studies, the idea of providing commissioning services independent of design teams and contractors appeared to be an opportunity that suited my experience.

2. What does Van-Fort do in relation to green projects?

Van-Fort which has been doing building commissioning and some M & E site coordination since the late 1990s as a third party resource. My involvement with LEED goes back to 2004, and includes acting as a volunteer member of the CaGBC technical committee for over eight years.

3. Your background is project implementation, commissioning and project management. Tell us about some of the green projects you've worked on – what were some of the most interesting/unique?

My role in construction management has involved some form of commissioning on projects going back to hospital and museum projects in the 1980s. As to green projects or projects using alternative system designs now commonly found on green projects, we have worked on many LEED certified projects and were the owner rep for the commissioning of:

  • The Canadian War Museum which made use of river water in lieu of cooling towers for cooling and as a source for non-potable water for toilet flushing.
  • The City of Ottawa Huntmar Police Station which made use of chilled beams coupled with a dehumidification unit on the building make up air for summer cooling. The ventilation system made use of low level introduction of outside air to occupied spaces. This project also had a non-potable water system collecting water from the roof for toilet flushing.
  • One two-storey office for computer support services that did make use of underfloor ventilation where the underfloor system was not understood by the design/build team, and projects in existing building making use of perimeter buffer zone systems where these systems also failed to perform as anticipated.

4. You have some strong feelings about underfloor ventilation. What would you like the green building industry to know about it?

I suggest that underfloor ventilation has been a bandwagon that many in the design industry climbed on without understanding the full impact to both construction and ongoing building operating. There have been many articles about UFAD but the two references that a designer should read for underfloor ventilation (UFAD) are: – ASHRAE Journal in October 2004 and the AABB (TABB TALK) newsletter issue No. 7 dated winter 2004.

As with any system there are pros and cons that need to be understood before committing to using a system. Also there is more to coordination of these systems throughout design, installation and commissioning than some teams may understand. I have worked in offices with this type of system and have been involved in commissioning of this type of system.

The biggest failures we have encountered were the sealing of underfloor plenums and the balancing of air flows due to lack of adequate static pressure in the underfloor plenum due to horizontal leakage between underfloor supply air plenums. This means good details for all contact surfaces along with M & E penetrations. Contractors will not do a good job of sealing underfloor plenums unless the design team provides details for these plenums at the same level and standard as most design teams prepare for building envelope penetrations.

Underfloor plenums need to meet the same leakage standards as a ducted supply air system. The floor diffusers do not perform if there is not enough static pressure and the energy cost to ramping up the supply fans to overcome plenum leaks should be a non-starter.  Quality control by design team during installation is also critical as if it is left to the performance testing during commissioning it is too late.

After occupancy we have observed occupants of the space not accepting the air being blown up their legs or under desk drafts and resulting in local craftsmanship being applied to the offending diffuser which is easily accessible at floor level. Of course when one occupant deals with their perceived problem, the effective air distribution is impacted and the air goes elsewhere with even more local involvement.

Think about it for air quality at the breathing level: clean rooms, laboratories and hospitals usually supply at the ceiling and exhaust near the floor. UFAD means that the office housekeeping had better be very good or the street dust will be swirled up into your breathing space. All stake holders in particular operation, maintenance and the Data/Communications teams need to understand what they are working with.  Occupant training is also needed.

So when using an UFAD system in a project there is a lot of coordination to be done between the access floor system along with the floor finish specification (not typically in the ventilation contractors scope), the plenum or wall construction (which may or may not be 100% in either the mechanical contractors or the general contractors scope). Then there is the test method and air leakage standards to be met by the underfloor plenums in what is effectively a supply air ducting system.

5. Given your background in commissioning and management, what are some of the key things you've learned about how to make a green project move more smoothly, and reach its goals quicker?

Better understanding of the basis for the design by all project stakeholders. Preparing or reviewing the owners project requirements (OPR) has made this clear and that there is a lot more than the OPR that needs to be clearly explained and discussed.

Also design integration particularly between the Civil, Architectural and Mechanical design teams. In particular, good details for ease of air flow within occupied spaces and good details for interior temperature control. There needs to be a good understanding of details by the construction team as to why the detail exists, and early follow up by the quality control personnel from the design team with less down loading of liabilities for quality control outside of the design team or to junior personnel with limited field experience.

6. Where do you think the future of green building is headed in the immediate or more long-term future?

I would hope the green building would drop the "green" as it is a bit over-used, and instead focus on the sustainable and lower energy use side of the discussion. It is needed to get clients to think beyond the project warranty period and get focused on the life-cycle cost of the projects, and by doing this there should be both an improvement in sustainability and energy use. Sustainability needs to emphasize maintenance as well as the energy operating costs.  

Re-commissioning is good and can help a facility but the largest impact is how well building operators understand the building design operating ranges along with operating limits and the ongoing maintenance is being done prior to systems failing.