Once Upon A Time… Comfort of temperature was the primary goal of the HVAC Industry. According to the website PubMed.gov, “Most illnesses related to environmental exposures stem from indoor air exposure”. Couple a home’s poor IAQ with your workplace and the result could be devastating to your mental and physical health. How safe is the Indoor Air Quality in your home or office space?
The core of the problem with Indoor Air Quality goes beyond the recycling of stale air. Sources of contaminants include cleaning solvents, paints, pesticides, CO2, building materials, radon gas, garages, even carpeting & furniture to name a few. These contaminants can cause a range of effects. Some exposures range from eye, nose, and throat irritation, to headaches, allergic reactions, even mortality.
Replace your air filters in a timely manner and consider room air cleaners, air purifiers, or UV lamps. Have your ductwork periodically cleaned and your HVAC system maintained to prevent carbon monoxide leakage should you have a gas furnace. Simple maintenance and room devices can remove or neutralize triggers for asthma or allergy sufferers. These simple low cost measures can go a long way to improve the safety & air quality of your home or office and the well-being of your family and coworkers.
COVID-19 & Pandemic Concerns.
Global pandemics such as COVID-19 raise new concerns. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) is a professional association seeking to advance heating, ventilation, air conditioning & refrigeration systems design and construction. ASHRAE provides guidelines for IAQ. ASHRAE Standard 62 – Ventilation for Acceptable Indoor Air Quality specifies minimum ventilation rates and indoor air quality acceptable for indoor occupancy… with the intention to minimize the potential for adverse health effects.
Early in April 2020, ASHRAE offered a study titled; ASHRAE Position Document on Infectious Aerosols. This study directly addressed COVID-19 and noted; “The risk of pathogen spread, and therefore the number of people exposed, can be affected both positively and negatively by the airflow patterns in a space and by heating, ventilating, and air-conditioning (HVAC) and local exhaust ventilation (LEV) systems”.
ASHRAE recommends that a portion of outside air must be introduced into a commercial building to maintain a healthy indoor air environment… But is it enough with the threat of pandemics?
ASHRAE 62 Recommended Minimum Outdoor Air Requirement
- 15 to 60 Cubic Feet Per Minute (CFM) Per Person
- Most Common Range is 15 to 35 CFM Per Person
- The Average Range is 15 to 20 CFM Per Person
ASHRAE’s thought on patients infected with COVID, a 100% full exhaustion of air is recommended. However, what’s the cost?
Is An Economizer The Solution?
The ASHRAE Study recites for non-healthcare buildings… “Increase outdoor air ventilation (disable demand-controlled ventilation and open outdoor air dampers to 100% as indoor and outdoor conditions permit)”, and “Keep systems running longer hours (24/7 if possible)”. An Economizer should be in every Rooftop Unit (RTU) in my opinion. They are necessary to effectively maintain the ASHRAE minimal fresh air requirements while offering free cooling with an optimal outdoor Temperature and Humidity range. To disable them when “Outdoor Conditions Permit” means they must be re-engaged when those conditions are no longer favorable. High humidity and extremes in temperature are problematic. Most HVAC RTU’s are not designed to handle the heating & cooling load required to condition these extremes with 100% outside air. Additionally, the cost of a 24/7 remedy under such circumstances would lead to astronomical power consumption costs to the building owners.
If you have an Economizer installed, you can set it to increase the outdoor air change rate. The change rate is described as how many times per hour you completely remove the inside air withing a space and replace it with fresh outside air.
The Energy Recovery Ventilation (ERV) Solution
An ERV allows you to remove stale, perhaps unsafe air from a building while recovering the heating or cooling with high-efficiency. Therefore, when the temperature outside is at zero degrees Fahrenheit, and 70 degrees inside, at an 80% ERV efficiency on temperature, the ERV will return 56 degrees to your RTU. An ERV coupled with a rooftop unit can significantly reduce the outside air load, which allows you to reduce the cooling and heating capacity of the RTU, offsetting the investment cost of an ERV.
Should ERV airstream cross-contamination be a concern? When the airstreams cross inside an ERV, there is a potential for the building’s exhaust air to leak through to the fresh outside supply air and return back into the building or space. AirXchange, the manufacturer of ERV wheels and cores (the critical transfer component in all of MicroMetl’s Engineered ERV products) and the manufacturer of choice for MicroMetl, states… “Some ERV units or sections are designed to allow for as much as 5% or 10% Exhaust Air Transfer Rate (EATR). This is within ASHRAE Standard 62.1 allowances and is the most energy-efficient for some spaces”.
ASHRAE is not a fan of this situation when addressing indoor spaces from infectious aerosols (Such as COVID-19) according to the April 2020 documentation. ASHRAE states “Bypass energy recovery ventilation systems that leak potentially contaminated exhaust air back into the outdoor air supply.” Bypassing the ERV can present a new set of issues if your RTU was down-sized when coupled with and ERV to meet the building’s load. So the new goal or solution is to prevent cross-contamination, and not bypass your ERV investment and overburden your RTU.
The subject of cross-contamination is a topic for another article. If you are a MicroMetl approved customer, you have access to our Online ERV Builder. The software offers the EATR information for each selection and allows you to inject alternatives to change that variable. Otherwise, contact MicroMetl’s Customer Service or Sales Representative to tailor an ERV to your specific needs. We can reduce and/or eliminate cross-over.
Control Those CO2 Levels
We’ve all experienced that lethargic moment when inside a room with poor ventilation when no amount of coffee can keep you awake. Elevated CO2 Levels can cause mild to dangerous physiological & mental conditions at varying levels, but can be controlled.
The Effects of CO2 Concentration
- ASHRAE Recommends Indoor Levels of Less Than 1.000 Parts Per Million (PPM) of CO2
- 1000 PPM In Under 2.5 Hours – Impairs Judgement, Decision Making & Thinking Skills On A Short Term Basis
- 2500 PPM In Under 2.5 Hours – May Render People Cognitively Marginal or Dysfunctional
- 5000 PPM – Headaches, Lethargy, Mental Slowness, Emotional Irritation & Sleep Disruption
- 60,000 PPM Within One – Two Minutes – Hearing & Visual Disturbances
- 70,000 PPM In Five Minutes – Death
CO2 monitors can be added to multiple MicroMetl products to maintain safe CO2 levels. Add them to an Economizer with Power Exhaust, or an ERV for on-demand control. Again, contact our expert Sales Staff & Customer Service department for your best solution.
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