EDITORIAL CAMPAIGN Building Tracing & IEQ

The overall energy impact (normalised for MMBTU) for each building is shown below: was retained to perform energy-impact assessments towards improving IAQ for three facilities – a K-12 school, hospital and higher education institution. The intent of the assessments was to evaluate the budgetary impacts of adhering to the latest ASHRAE standards, which were instituted in response to the pandemic. The studies looked at the following ASHRAE recommendations:

Small increase due to large baseline of energy use for hospitals, since hospitals typically utilize a large amount of outdoor air as standard practice.

Large % increase since K-12 schools typically utilize a low amount of ventilation air, compared to hospitals and higher education. Localized humidification is approximately 3% of increase.

15.0% As expected, due to increased ventilation. Localized humidification impact is approximately 5%.

> MERV 13 filter replacements

> Airflow adjustment (purge cycle): Increase air-handling equipment run hours – 2 hours pre-/postoccupancy (or equivalent of 3 ACH) in the attempt to “purge” the space of stagnant air and bring in fresh, outside air prior to occupancy.

> Local humidification: Maintain minimum RH of 40% for atrisk spaces (nurses’ offices, administration areas, etc.). Note that this factor did not have a major impact on the hospital, as it is mostly humidified already.

> BMS modifications: Increase OA amount by three per cent, on average, for all air-handling units.

The wide diversity in the increase in energy use for the improved IAQ can be simply explained that hospitals, in general, utilise a large percentage of outdoor air, while K-12 buildings typically have a smaller baseline. In short, since the baseline is so high for a hospital, increased ventilation doesn’t have a notable effect.

While no one is proposing, at least right now, that the above recommendations be mandated, the magnitude of the increased energy use for improved IAQ should give one pause for consideration. The K-12 increase is reflective of what we can expect to experience in typical office buildings, retail centres, etc. Certainly, if buildings were to be directed to improve IAQ, even a 10-20% increase would make the current carbon target reduction targets that much more difficult.

But it’s worse than that…

A little secret in the HVAC profession, especially in the energy engineering sphere of business, is that too often sub-optimal HVAC systems have reduced energy consumption, because the building owners aren’t paying to maintain or even operate them! If we simply forced building owners to comply with current building code (for buildings with non-operable windows) we can improve IAQ dramatically. However, if we are to have an informed conversation on reasonable reduction of carbon, we need to build this increased energy use into our carbon footprint baseline.

A path forward – reducing carbon while improving IAQ

I believe we can reconcile the carbon reduction challenge with improving IAQ. Meeting the aggressive carbon reduction strategies in front of us is going to require a “greening of the grid” – that is, a turn towards nuclear power, increased hydrogen power and increased renewable power, etc. Simply put, you can’t reach targets of two-thirds energy reduction through energy conservation. The only way to meet such an aggressive target is to electrify buildings, which would be very expensive.

In parallel, we can improve building energy performance while also improving IAQ, which would minimise the strain on the grid. Steps which I recommend, from least expensive to most expensive, are as follows:

> Equipment scheduling: Ensure equipment is scheduled properly, including energy-saving features, such as airside economiser.

> Continuous commissioning: Ensure all existing building controls are working correctly.

> Ductwork sealing: Ensure ductwork is properly sealed to avoid conditioning of “wasted air”.

> Air-to-air heat recovery: While expensive to install, air-to-air heat recovery is a fantastic way to dramatically reduce carbon footprint, while improving IAQ.

While we, as a society, are engaged in a noble challenge to reduce our collective carbon footprint, this is a shortsighted goal if we don’t ensure adequate indoor environments as an equally important goal. We must remember the law of unintended consequences, so that the cure is not worse than the disease.

CPI Industry accepts no liability for the views or opinions expressed in this column, or for the consequences of any actions taken on the basis of the information provided here.