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How a Heat Recovery Ventilator Can Make Your Home Healthier
Indoor air quality has never been a more pressing or popular target than it is today. With smoke from wildfires all over the West and the continuing global pandemic of COVID-19, many of us are wondering whether our indoor air is safe. The good news is: it can be, with the right systems in place.
November 5, 2020
Indoor air quality and ventilation are hot issues right now. With the COVID-19 pandemic raising questions about viral spread, and wildfire smoke recently forcing many of us into our homes, it makes sense why many are beginning to wonder about the safety of their indoor air.
In our last post, we discussed options for retrofitting an existing HVAC system for more powerful filtrations and better air exchange. Here, we’ll discuss the most useful system for new construction or remodels where you’re installing a new HVAC system.
It’s possible to design and install systems that address the issues of health and clean air.
We know ventilation is an important component of healthy living, and luckily, it isn’t actually a difficult problem to solve.
The first step is to build better. A well-sealed building allows us to control what air comes in, where it comes from, and how much it gets filtered. Then our ventilation system can be much smaller and more efficient.
The next step is to install a balanced ventilation system that brings in the same amount of filtered outdoor air as it exhausts in stale indoor air. Imagine you installed two fans: one pulling in outdoor air through a filter, and the other exhausting the indoor air at the same rate. You would have continuous air movement and replacement — just what we want.
Solving the Problem of Temperature
The two-fan system just mentioned would waste a lot of energy since it would be bringing in outdoor air at whatever temperature it is that day, and the indoor air (that you spend money and energy on to keep at the right temperature) would be literally thrown out the window.
To solve this problem, some very smart engineers developed a device called a Heat Recovery Ventilator, or HRV. This device is nearly as simple as the two-fan system but, instead of just letting air enter and exhaust at whatever temperature it wants, incoming outdoor air passes through an air-to-air heat exchanger at the same time that the indoor air is passing out through this heat exchanger. While the two air streams are physically separated, the material of the heat exchanger allows heat to flow between the two moving air streams.
As an example, in the winter, if the incoming outdoor air is 32°F and your outgoing indoor air is 70°F, the heat exchanger allows that heat from the warm indoor air to flow into the cold outdoor air and your house receives 67°F air, raised from the 32°F air that would be brought in if you opened a window. This provides you with outdoor air at a comfortable temperature without losing all that heat you paid for to keep you warm.
Why an HRV System Works
An HRV unit is constantly filtering the incoming air, and thus, is able to provide an improved and healthier indoor environment by replacing indoor air on a regular basis with clean outdoor air.
There are different levels of filtration available, including the MERV 13 filters, which we discussed in our previous post about updating your HVAC system. These units get ducted to every room in your house or apartment, which means it is supplying filtered outdoor air to your living spaces and bedrooms, and exhausting air from your kitchens, bathrooms, and laundry rooms instead of the standard bath fans. The constant flow of air at a low speed means the air in your home is being exchanged many times a day, both filtering out the viral or smoke particles and diluting or removing other pollutants from your indoor environment.
Invest in Year-Round Benefits…
Not only is an HRV beneficial during a pandemic or wildfire, but it also provides benefits year-round for asthma and allergy sufferers, along with people without chronic respiratory issues. We have lots of sources of pollutants in our homes (cooking, pets, perfumes, and VOCs from furniture, carpet, paints… the list goes on!) that get expelled and diluted by the constant air exchange that an HRV provides.
It also can provide you with better sleep by removing the humidity and carbon dioxide that typically builds up in our bedrooms from our breathing throughout the night.
…Without it Costing an Arm and a Leg
Including an HRV in your project is not cost-prohibitive. Typical costs premiums for an HRV system is 1% or less of the construction cost, and the health, comfort, and energy-saving benefits you see result in a payback several times higher than the initial costs of the system.
This post is part of a series discussing ventilation and indoor air quality in response to the ongoing COVID-19 pandemic and worsening air quality along the Pacific Coast due to wildfires.
More From This Series on Ventilation and Indoor Air Quality
Options for Updating Your HVAC System for Better Indoor Air Quality
There have been a lot of discussions and varied information on how the built environment affects the spread of COVID-19. Now we are also seeing more intense wildfires and smoke than we have seen in the past decade. With both these environmental issues keeping people indoors, healthy ventilation strategies are more important than ever. Read on in Options for Updating Your HVAC System for Better Indoor Air Quality.
Tips for Ensuring Your Home Has Good Air Quality
With wildfire season continuing into the late fall and a global pandemic still keeping millions of people indoors, there's a lot going on in the world. Both these natural disasters have brought to the forefront the importance of ventilation for your health: well-designed ventilation in buildings is important to address present and future pandemics, wildfires, and other airborne pollutants. Learn more in Tips for Ensuring Your Home Has Good Air Quality.