Designing HVAC systems around performance-based ventilation enables buildings to operate with smaller equipment, but the required calculations have been overly cumbersome — until now. New software is able to expedite the process, proponents say.
ASHRAE Standard 62.1, which is used by many governments as code for ventilation and acceptable indoor air quality, provides two primary methods for calculating minimum ventilation rates — ventilation rate procedure, or VRP, and indoor air quality procedure, or IAQP.
As energy costs rise and demand grows for healthier, more sustainable buildings, the industry is giving serious attention to IAQP, which can reduce the energy use of HVAC systems by 20%, experts say.
IAQP has been a part of ASHRAE 62.1 for more than four decades, but it remains largely underused because of the time required for engineers to make calculations, according to workplace solutions company Fellowes and HVAKR. The majority of the time, ventilation professionals will default to VRP, a prescriptive method that is not actually based on analyzing the quality of air inside a space, but rather uses “rules of thumb,” Davis Muxlow, co-founder and COO of mechanical system design technology company HVAKR, said in an interview.
New technology that helps automate some of these calculations may be the key to unlocking IAQP as a more popular pathway, according to Jason Jones, director of air quality management at Fellowes. Last week, the company announced the launch of an enhanced IAQP workflow within HVAKR’s holistic mechanical engineering workspace platform.
With VRP, “you’re diluting the space based on these rules of thumb. You’re not actually calculating the quality of air by comparing concentrations of contaminants to their healthy limits,” Muxlow said, “whereas IAQP is doing all that.”
IAQP lists 14 design compounds or contaminants that need to be assessed to make sure they are below the unhealthy threshold inside the space, he said.
“IAQP actually calculates the outdoor concentration of these 14 compounds, what the indoor generation rate is [and] it does this mass balance equation to see if the concentration in my space is below the limit,” Muxlow said. “You’re calculating how much outside air to bring in to ensure that all your contaminants are below this unhealthy threshold, which is very computationally heavy. This is why a lot of people were doing VRP until now. It gets very difficult to get all that data, and that would also include [factoring in] air cleaners.”
The difficulty of getting all this data, along with the need for air cleaners to keep contaminants below these thresholds, is why many people are only calculating airflow with VRP, he said.
HVAKR’s platform and integration enable engineers to run calculations quickly while Fellowes’ air-cleaning products can be used to ensure all contaminants are being filtered out of the air, according to Muxlow.
“Essentially, they can drop in a set of floor plans and get a complete mechanical design out on the other end. From there, they can spend their time making the design as good as possible,” he said. Instead of just trying to get something out to meet a deadline, they can actually spend time comparing options to see which is the most efficient for each project.
This is where HVAKR fits in, Muxlow said. “Normally an engineer doesn’t have the time or luxury to run that analysis, even though in a lot of cases it would be a benefit to the project,” he said. “It would save on annual energy consumption; it’s just this huge [challenge] to do that calculation ... and analysis.”
The partnership with Fellowes is intended to build that IAQP analysis into the HVAKR program to run parallel with normal activities that an engineer has to do. As soon as they’re done, “they can just compare, ‘What are the results over here versus this?’” Muxlow said.
In many cases, IAQP results in lower ventilation required, which means less outdoor air needs to be conditioned, he said. That means systems can be smaller and don’t need to work as hard.
Currently, only about 1% of projects use IAQP, according to Jones, but that number is rising as energy costs spike and facility teams see it as a way to rein in use.
“It is the energy that’s driving the conservation. We joke about the fact it’s called indoor air quality procedure, but it’s all about the energy,” Jones said. “The air quality is almost a side benefit to the energy savings that you’re capable of achieving by reducing the sizing of your HVAC system.”
Net-zero initiatives and green and healthy building certifications like LEED and WELL are also contributing to the use of IAQP, “but the financials of it really make it palatable once you see the numbers,” Jones said. “You can see a 20% reduction in energy of your HVAC system. It went from a technology that you may or may not be something we want to invest in to … an absolute no-brainer.”
Although many efficiency technologies are going to cost more up front, this is an instance where operators can see upfront savings and long-term operational savings, he said.
The change in calculations can have cascading benefits, Jones added, for example by reducing the need for costly structural upgrades. “We’re seeing it unlock a lot of options for people that didn’t know they had,” he said.
“We’ve seen this happen … where the increased VRP calculation, because of a new code or change in occupancy, requires a system that’s simply too heavy for the structure or … where it’s going to put us over the energy capacity of the building,” he said. “That’s … probably the most exciting. Some of these engineers [have] painted themselves into a VRP corner, and IAQP has given them a path forward that stays within budget or even under budget because we’re avoiding these upgrades or these unforeseen challenges that VRP causes, simply because of the way the math works out.”
