Oxygen8: High-Efficiency DOAS Systems
How do we best ensure sustainable indoor air quality and energy-efficient air handling?
Do we have to consume more energy to meet more stringent ventilation requirements?
We posed these questions to Erdem Kokgil and Johnnie Allan of Oxygen8, the Vancouver-based manufacturer of innovative heat and energy recovery ventilators.
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HRV vs. ERV
As a quick refresher, heat recovery ventilators (HRV) recover only sensible heat, with no change in moisture or humidity levels. Energy recovery ventilators (ERV) recover heat and moisture, decreasing OA temp and humidity in summer and increasing them in winter.
These devices are rated by their SRE (sensible recovery efficiency) performance. Wheel-based recovery devices have higher performance (70–90% SRE) but also have moving parts that cause problems and allow for a small amount of cross-contamination of airstreams. Fixed-plate exchangers (60–85% SRE) offer a low-maintenance alternative.
Wheels are primarily for high flow-rate applications (over 5,000 cfm), and fixed-plate devices are usually specified below that rate. However, new fixed-plate technologies, like those from Oxygen8, are viable for 5,000-10,000 cfm applications.
The Benefits of Sustainable IAQ
Our goal is to provide more fresh air into a building while decreasing the energy consumption it takes to accomplish that.
Scientists are developing more data about how buildings affect occupants’ cognitive functioning. It’s easy enough to meet ASHRAE ventilation minimums (usually 3–4 air changes per hour). However, according to the Harvard School of Public Health, the ideal target is 5–6 air changes per hour, twice the minimum.
A greater number of air changes brings down the levels of VOCs and CO2 in building air and helps remove airborne particulate. This summer, there’s been much focus on removing PM2.5, the particulate in wildfire smoke.
Studies show that people display better cognitive functioning in buildings with better indoor air quality. They take fewer sick days per year and demonstrate a 2–10% increase in productivity in higher-ventilated spaces.
High-efficiency energy recovery is an ideal way to achieve this ventilation increase without spending vast sums on traditional increases in air changes per hour.
Oxygen8’s High-Efficiency Energy Recovery
Oxygen8 set out to deliver customizable ERVs, making them compact, quiet, and highly efficient. It only manufactures fixed-plate core devices in crossflow and counterflow models ranging from 300–10,000 cfm.
The company’s ventilators can be configured for Daikin VRV or hydronic integration.
It manufactures all its units in Vancouver, BC, including its cores and panels, to decrease lead times and have a more reliable supply chain.
Oxygen8’s devices recover up to 75% sensible heat with an ERV core and up to 85% with an HRV core. Their different models apply to different climates and buildings. In Minneapolis, there’s a sizable demand with schools for fixed plate cores and hydronic integration.
Counterflow heat exchangers are common in Europe and are becoming more common in America. These units are a bit longer than crossflow-type ERVs, which allows more space for more space for heat transfer.
Oxygen8 ERV cores use polymer membranes instead of the desiccants that you’ll find on wheels. These are designed so only heat and water vapor can pass through the membrane.