20+ years out

What critical environments and the world’s healthiest, most sustainable buildings have taught us about ventilation

By Dan Diehl

It has been a year since the pandemic changed our lives. Many say that the ways we work and learn in buildings have changed forever. Someone asked me recently what this experience has taught me about making buildings safe to reoccupy. I quickly answered, but then I realized it wasn’t the right question.

The urgent need to make buildings safer has led to a range of improvised solutions, some of which are beneficial, but not sustainable; others not proven to be effective, but allow building owners to demonstrate they at least must do something. I realized that to chart a path forward, we needed to tap a much longer and more telling history of data and learning—one that was hiding in plain sight. So, after a week or reflection, I should have responded: “Do you mean, ‘What we have learned over the last 20 years about the importance of ventilation in healthy and sustainable buildings?’” We could go back further to examine lessons learned regarding efficiency in buildings, which has been a focus since the 1970s. But the core built-environment challenge for the post-COVID world is how to balance healthy building design and operation with efficiency and sustainability.

Fortunately, there is a 20-year history of forward-thinking building owners achieving that exact balance in labs known as critical environments. Because of the potential health and safety risks posed by airborne contaminants, labs have stringent air quality requirements. Historically, those requirements were met by providing very high volumes of 100% outside air at all times. That made labs among the most energy intensive spaces to operate. The Smart Labs Program was created with the idea that through innovation you could make labs more energy and carbon efficient while increasing human health and safety. Based on the Smart Labs data, do we really know what’s needed to make dramatic improvements on both fronts in all commercial buildings? I think they do, based on hard evidence and analysis of actual long-term results in close to a thousand facilities worldwide.

Three key lessons emerged from our experience with Smart Labs: 1. We cannot control what we do not accurately measure 2. Healthy buildings require fresh clean air and active ventilation management 3. We must avoid the Healthy vs. Sustainable Trap Accurate Measurement in critical spaces/labs

The foundation of healthy and sustainable labs started with the requirement for accurate measurement of the air quality in the space. Prior to this, labs were designed with 10 to 12 Air Change Rates (the volume of air, measured in cubic feet per minute (CFM) that goes in and out of a room in one hour). This high, continuous flow was a design choice done solely to solve for health and safety. But it was extremely expensive to operate. The results were perceived as safe. In addition, operating costs were high and spaces were not environmentally friendly, as research spaces were the largest offenders of both greenhouse gas emissions and $/ square foot energy consumption. Labs often were five to seven times as energy intensive as similar sized non-lab facilities. The challenge to improve these systems began with the simple question—

what are we looking to control and ensure in these spaces? The answer was obvious: clean and safe air for the researchers. The next question was, “Can we make sure harmful chemicals and small particles are removed from the space and exhausted from the building and could this be done much more efficiently/sustainably?” The overall strategy for maintaining safe, healthy air conditions at lower cost and with lower carbon emissions was to shift from a fixed, predetermined air change rate, to a dynamically controlled air change rate that is based on conditions in the space. This approach required very accurate, reliable air quality measurement. That was achieved with an innovative system architecture that allows a single set of expensive, industrial quality sensors to measure the air quality in multiple lab spaces at an affordable cost per space.

Over the 20 years that DCV has been successfully deployed in critical environments, researchers have identified the science-based healthy building parameters that we now know determine the health of indoor environments.

Lesson 1 — It starts with Accurate Measurement

All functioning engineered (non-biological) systems require “accurate measurement” of inputs and outputs to perform properly and to ensure desired results are being achieved. This statement, while overlooked, is a fact. For any dynamic system, we must understand how varying inputs will affect the system’s performance. Lesson 2: Effective ventilation — Controlling the amount of healthy air based on Accurate Measurement

The safer, more efficient solution was to use very accurate air quality sensors to dynamically control the amount of ventilation being introduced to the lab spaces. Ventilation is by definition the “provision of fresh air to a room or building.” This actually is a pretty poor definition of what we really want and need in a healthy, sustainable space. What we require is that clean air, which should be measured and confirmed, is both supplied and exhausted from that space. This is exactly why Air Changes per Hour (ACH) is the measure of the ventilation rate in labs and ORs. Historically, design guidelines for commercial and institutional buildings used the ventilation rate procedure (VRP) method which, like old lab designs, sets a prescriptive minimum ACH based on the size of space and “expected” occupancy levels. More recently, ASHRAE has allowed for the IAQP method where ventilation is controlled by the measurement of the air quality, allowing for lower ventilation rates, greater HVAC system efficiencies and higher confidence that the contaminants of concern are being eliminated from the breathing zone. This of course, echoes the Smart Labs innovation. If we can use this approach to achieve greater efficiencies while delivering safe, healthy air—it seems like a ‘no brainer’.

Demand Control Ventilation— providing the right amount of healthy air, where and when it’s needed

But you may be thinking, so what is the right ventilation rate, and do we really want to operate buildings with less than maximum ventilation? The answer, as we learned in critical environments, is that it depends. What we want is more air where and when needed. Yes, we can have lower ventilation rates when the air is clean and meeting science-based standards, but there are times when certain areas of a building need

increased ventilation—prioritizing health and well-being over efficiency when necessary. This flexible approach is called demand control ventilation (DCV). DCV is often misunderstood, even by people in the HVAC industry who equate DCV with an across the board reduction in air flow. Over the 20 years that DCV has been successfully deployed in critical environments, researchers have identified the science-based healthy building parameters that we now know determine the health of indoor environments. These are small particles, carbon monoxide and dioxide, relative humidity, and total volatile organic gases.

Lesson 3 — Avoid the Healthy vs. Sustainable Trap

As we learned in critical environments, providing significant ventilation in spaces when they are clean is wasteful and can be costly not just in energy expense but also in carbon emissions. Because the built environment accounts for as much as 30% of such emissions, building owners will be under increasing pressure to reduce carbon emissions over the next twenty years as we move toward a net-zero carbon world. At the same time, due to the growing awareness of fresh, clean air’s impact on health and cognitive function, building owners will also face more and more pressure to increase ventilation rates in all work and educational spaces. These two imperatives of increasing health and sustainability are seen by many as conflicting: goals that must be traded off against one another in a zero-sum game. Under the old design criteria of fixed ventilation rates, they are in conflict. That conflict leads to what we call the Healthy versus Sustainable Trap, a sub-optimal cycle in which building owners periodically over-ventilate when health is the most urgent concern and under-ventilate when sustainability becomes the more top of mind issue. But we now understand that it is fixed ventilation rates that exaggerate this conflict, and that the way out of the Healthy versus Sustainable Trap is DVC with accurate sensing and control of science-based healthy air parameters. Our learning from critical environments confirms this optimal solution. To cite one of many examples, a well-known University of California System school focused on ventilation management in 17 buildings. The results: 61% efficiency gains while achieving the best safety record compared to all other peer institutions. We know that historically, non-lab facilities won’t produce that same amount of efficiency gains, due to their use of return air systems (versus 100% outside air) and lower initial fixed ventilation rates, but there is a huge “but”…occupancy rates will not return to previous levels for many facilities, and/or they will vary more dramatically going forward. In addition, the emerging consensus is to use higher fresh air rates in all buildings. This, for sure, means that if left unchanged or unmanaged, there is a huge potential to significantly over-ventilate, waste a lot of money and needlessly negatively impact sustainability goals. That is the big opportunity for the future of healthy and sustainable buildings: optimize these two seemingly conflicting requirements, in many cases improving total performance in both.

Overall, the path forward is to apply the lessons learned from 20 years of experience in labs to all commercial and institutional buildings. The pandemic has made all of us aware that all buildings where people work or learn are critical environments. The next step is to apply the three big lessons learned to all of those spaces: > Start with accurate measurement of science-based IAQ parameters > Deploy DCV using accurate, roomlevel feedback on the parameters > Operate the system to maintain the Healthy Building parameters in the most environmentally and economically sustainable way possible CCR