Making Sure Commercial Buildings Perform Optimally with Commissioning — And then Recommissioning
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It can be challenging to keep all of the systems of commercial building performing at their best – particularly the way many structures are designed these days, contractors say. As for existing buildings, practically every structure has its own set of issues – which spell untold opportunities for recommissioning to make sure the building as a whole performs optimally.
Commissioning Systems During Construction
There can be design issues and construction issues that impact the performance of systems within commercial buildings, and because the world is “ever more complex,” there’s a “whole series of convergent problems,” says Steve Saunders, chief executive of Tempo Mechanical in Irving, TX.
“The price of real estate is growing and to make the economics work on the land, commercial buildings have to be taller,” Saunders says. “As a result, now developers are changing the building envelope system to steel or concrete and creating all new and different issues with the skins of the building.”
Tempo Mechanical does a fair amount of commissioning, mainly on mixed-use buildings – mid-rise and high-rise structures with apartments and retail and office space on the lower floors. One potential problem is possible air intrusion with high water content, due to weather conditions that bring changing dew point conditions to the indoor and outdoor air conditions – and which can then breed microbial organisms.
“Now, we even have situations in winter where we can have created microbial growth,” he says. “The exterior envelope can get so cold that the temperature of aluminum window frame drops below the dew point, that condensation forms – creating a whole new set of problems for mechanical systems.”
More insulation or better thermal breaks on the windows may be needed, but contractors and building owners need to be aware that these changes could have a big impact on load calculations, Saunders says.
“There are also other issues that we’re beginning to worry about,” he says. “A few months ago, low-income housing in a London building caught on fire and spread up the skin — the building exterior. There were no fire retardants in the exterior wall insulation. The fire spread through the exterior of the building, emitted harmful chemicals and became an issue in itself.”
Due to the shortage of quality labor in the mechanical trades, designers are now considering mechanical systems that are less labor intensive, Saunders says.
“However, some of these ‘solutions’ create problems as great or greater than the driver for change,” he says. “At present, there are few simple, clear answers.”
Tempo Mechanical also serves as a commissioning agent for large commercial buildings – an independent third party hired to inspect the mechanical systems that other contractors have installed. The firm has found problems in the ventilation systems in mixed-use buildings due to complications in the assembly and installation of some of those products. As a result, the systems did not operate properly, which contributed to building performance problems, Saunders says.
“The ventilation systems were bringing in hot humid air every time the air handler ran,” he says. “Likely, the extra humid air helped increase microbial growth in the apartment units. After we identified the problem, we worked with both the owner and the contractor to recommission the systems so they would operate as designed.”
Recommissioning Existing Commercial Buildings
When a building is originally put into service, all of the systems within that building – whether its HVAC-related, lighting or building automation – have been set up and tested for the highest efficiency and most comfort for the tenants, says Tony Yanniello, operations manager at Del Air Mechanical in Knoxville, TN.
“However, just over the course of a few years, those buildings can be altered, both from internal staff or other contractors coming in and out,” Yanniello says. “So it’s very important for us to come in and recommission the systems, to make sure the building again performs to the specifications of the architect or engineer.”
Del Air Mechanical’s team recommends taking a baseline from when the building originally commissioned, and during various occupancy times, and comparing the results to how the building’s systems are performing currently. The teams finds that many times, they need to make adjustments to get back to how the systems were set up, to perform optimally, most efficiently, and for the most comfort.
“Even when buildings have automation systems, a lot of operators don’t understand the complexity of the HVAC systems, and they make adjustments to reset temperatures or change the air flows in one part of the building that can impact other parts of the building,” he says.
Del Air Mechanical has a building automation division that also helps with lighting, not only for energy savings, but also to help make a better atmosphere for tenants, and to set the proper lighting for the task at hand, Yanniello says. The division can also set the automation system to increase and decrease lighting output based on the amount of daylight that’s coming into the building.
The firm also has a dedicated sales person who focuses on filling maintenance contracts, building relationships with facility directors, while all of the sales staff tries to sell maintenance contracts when they can, says Lori Sentell, Del Air Mechanical’s project team leader
“For optimal building performance, owners and managers need to keep their maintenance up-to-date with a local provide,” Sentell says. “They should also have someone on site to take care of basic things, like filter changes, when needed.”
When the contractor initially sets up systems, its team then goes out to the commercial building to conduct quarterly performance tasks, to make sure everything is working properly, so that repair costs can be kept down.
“We have annual contracts, but if they don’t cancel at the end of the contract, the contract automatically updates and rolls over into another year until otherwise notified,” she says. “In the contract, there is verbiage that we will cancel upon written notice – otherwise the contract will renew itself each year.”
Under a typical scenario the original commissioning is part of the construction contract with the general contractor, and at that point, the owner of the building only has the typical one-year manufacturer warranty on the system, Yanniello says. That’s why Del Mechanical’s team goes back to the building’s owners and explains to them the value of recommissioning, of making sure that everything is tuned and operating properly.
“We want to start the conversation almost immediately after the building is turned over to the owners, to talk about the value of preventative maintenance,” he says. “Even though the building is still new, there are still maintenance tasks that have to be done – things still have to be cleaned and adjusted for the system to perform optimally. Then we build the larger picture by having us assist with maintenance.”
Michael L. Ritter, Jr., co-owner of Great Lakes Heating and Air Conditioning in South Bend, IN., says that when his firm recommissions commercial buildings, “nine times out of 10” it’s for business owners who had the work on their own home.
“They usually tell us that their house is performing amazingly, and would like for us to do the same to their business facility,” Ritter says.
“When we recommission commercial buildings, we like to talk to the individuals in the building,” he says. “Typically, the issue is going to be that a person who has their own office is not comfortable, but the rest of the people in the building are fine. There are zoning or mini-split systems to handle that, with different thermostats so that everyone is happy.”
But some office buildings can’t have split systems, so instead Great Lakes can do mini-splits — split systems with one outside unit that can be connected to up to eight inside units, Ritter says. The inside units are similar to window units — but are “infinitely quieter.” Alternatively the firm can put in a residential system that is controlled with automatic dampers using multiple thermostats for various rooms and offices.
“The aesthetics of the building determines the ductwork, and if it’s really large or exposed, we have to do mini-splits or linework – installing garden-hose-sized refrigerant lines versus ductwork that are much easier to conceal,” he says.
Tempo Mechanical also recommissions smaller commercial buildings, Saunders says. Every one is a custom situation, and every building that has been operating for at least a year has a business case for some form of recommissioning, including the building his own firm occupies.
“There are a lot of complicated interactions different elements of air coming in or going out of humidity-creating devices,” he says. “Moreover, when changes are made to systems for greater human comfort, that can impact the building and also on the energy use of the building – virtually every building has an opportunity for recommissioning.”
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Posted In: ACCA Now, Building Performance
