Post-Pandemic Indoor Air Quality Seminar

Each month since April 2020 the Central Virginia Construction Specification Institute Chapter has hosted online seminars to promote communication within the industry. This important task of sharing information, having discussions, and learning from each other is the core reason CSI exists, to build a stronger industry. This month we are thrilled to welcome Chris Shifflett, PE, CHFM, LEED AP to discuss how post-pandemic indoor air quality will be viewed, understood, and controlled.

Register HERE

April 21, 2021

Noon – 1:00 P.M. EST


Summary: This session will consist of the following topics: Overview of air cleaning technologies, most common and widely used technologies (UV light and Bi-polar ionization), Filtration (MERV & HEPA), code required minimum ventilation, and ASHRAE and CDC recommendations.

Chris joined Blauch Brothers in 2017 and is currently the Mechanical Engineering manager. Before Blauch, he has a diverse background in HVAC and plumbing industries. He has held positions such as pipefitter, MEP consulting engineer, health care facility engineer, and professional engineer for other mechanical contractors. Through his past experience with health care facilities, indoor air quality focus is nothing new to him.

The air we breathe and why design matters

We have never thought so much about the air we breathe as we do now. After a year of working remotely, I returned to the office this week, sharing space with four other businesses. I also had a few people drop-in, from delivery drivers to clients to friends that I had not seen in a year. This was a huge change after a year of almost never leaving my house. Of course, after this past year of a virus that spreads through airborne particles, this is a huge change. The air we breathe has a direct impact on our health and therefore the design of our buildings matters.

Chesapeake Western Depot harrisonburg

Indoor air can be very unhealthy, even outside of virus spread. Smoke, mold, and chemicals along with other people contribute to what is in your air. All of these things in your air can be harmful to human health. When you think of air pollution you often think about smokestacks on industrial building sites or car exhaust. However, that is just a small part of the picture.


The air in your home comes in and gets trapped inside. It comes in when you open doors and windows of course, but it also comes in through your walls, crawl space, and attic. When the wind blows on one side of your home that exterior wall becomes positive pressure and the opposite wall becomes negative pressure. This pulls and pushes air through every gap and cracks in your house. This makes your insulation, carpet, drywall gaps, window edges your air filter – air filters that never get changed or cleaned.

basement insulation

Air is lazy, it looks for the easy path to escape. Easy gaps like electrical outlets, light switches, attic access all become paths for air to come into the house, bringing with it humidity, spiders, pollen, dust, and dirt. Your ductwork run in unconditioned spaces also becomes a conduit for dirty air bypassing the filter intended to clean your air.

Air Leaks

Chemicals in your building products are released into your air and you breathe them in. NO-VOC paints have become really popular, but not the only option. Off-gassing from glues, furniture, clothing, cabinets, paints, cleaning supplies, detergents, and even food are released into the air of your home causing a chemical cocktail that has impacts on your health.

No VOC Paint

When we design a custom home I always encourage our clients to allow us to write a project manual setting the performance standards for the HVAC system, airtightness of the thermal envelope and protects the inhabitants of the home. This performance standard is a critical element to protect the homeowner and to set the standards for the builder to complete. Without this document, you are leaving these performance standards to the builder and his subcontractors. While they may also be very concerned about indoor air quality, their priority is to make sure you are comfortable which is the source of most client’s perception of quality. We need to raise the bar and also talk about the air we breathe and the importance of setting high standards for indoor environmental quality.

Duct Work is Key to a Healthy Building

Duct work is a key to a healthy building. While there is not any one single thing that can be done in a building to achieve healthy indoor air quality, duct work is a critical element in the system. On one of our current projects at a local church, we are in the construction process to mitigate indoor air quality and water intrusion issues. Facilities of this scale are difficult to manage without a full-time building maintenance team. In this case, issues arose which further complicating things; decisions during a construction job 25+ years ago to cut construction costs have ended up causing indoor air quality challenges. The elimination of a fresh air distribution system as a cost cutting factor increased the potential for indoor air quality challenges for instance.

ductwork installation

Added complications

At the time, it was acceptable to use fiberglass insulation inside of duct work to control noise from the mechanical system in the sanctuary. This fiberglass insulation captured dust and dirt that flowed through the duct work. The dust and dirt provided food for mold growth, and multiple water leaks throughout the structure have added to the complications in this building. The lack of fresh air ventilation, technology available for HVAC at the time, lack of regular preventive maintenance, no dehumidification systems, and high humidity levels have led to this need for a major renovation.

ductwork installation ductwork installation

Duct work storage and protection

During the renovation process, it is critical to protect the HVAC duct work that is being installed. A construction site is messy and dusty on a good day. This one already had indoor air quality issues prior to construction. The mechanical contractor, Excel HVAC is sealing all the duct work that is being installed until it is sealed in place. They are also storing duct work that is not currently needed off site to keep it away from the dust and dirt on site. These simple steps protect the ducts to keep them clean and free of damage.

ductwork installation ductwork installation

Installation of Duct Work

Once the duct work is installed, all the joints need to be sealed. The vents should be covered until the system is activated, which only happens after all the dirt and dust of construction has ended. Sealing joints in duct work is done with mastic glue and mastic tape. These strategies are geared towards keeping dust and dirt out of the ducts during construction and operation of the system.

These key elements focused on duct work are only one part of the solution. We are also addressing roofing, flashing, and gutter issues. Materials that are impacted by mold are being removed and replaced. This is a complicated project with many moving parts. Working with an integrated team approach using Suter Engineering to design the appropriate HVAC system, and a qualified general contractor, Herr and Company, to manage all the team members is the best strategy overall to achieve the best final solution for this project. Stay tuned for more information as the project continues.

Be sure to ask for healthy indoor air quality in your new home.

There are some common things on the wish list for most custom homes. Clients want an open floor plan, lots of light, a beautiful kitchen, luxurious master bathroom, and connection to the outside. However, it is not often asked for – healthy indoor air quality.

Harrisonburg custom kitchen

Materials, structure, and the heating, ventilation, and cooling systems all contribute to indoor air quality. Making the right selections in all these areas is critical.

living room renovation


There are common elements that impact indoor air quality. A fireplace is a leak in the building envelope. When there is a leak, it will either bring dirty air into the home or pull dirty air through the building envelope into the home. This also happens with restroom ventilation fans, crawl space, and duct work.

Penn Laird Custom HomeCrozet Renovation


If the ductwork is not tight, it will actually spread dirty air around your house. Insulate it right and seal it tight.

IMG_0731encapsulated crawl space

Building Envelope

The building envelope is critical in the design of a home for healthy indoor air quality. Keeping the air from moving through the walls will allow you to filter make up air through a filtration system. This will, along with a fresh air system, keep the air flowing through your house healthy and clean.

DSC06785Indoor air quality


Also, and this one has big impacts to durability and indoor air quality, keep the water out of the wall system. Water infiltration in your home will contribute to indoor air quality faster than anything else.


Finally, the materials used in your home impacts indoor air quality. Do the materials you use have VOC’s? What chemicals will they off gas into your air? Are they easy to clean? What do you use to clean the materials used? All of these questions impact indoor air quality and should be considered.


It is not going to be on the top of your list, but include healthy indoor air quality when building or renovating.

Should my new house “breathe?”

Ask any seasoned carpenter (that does not understand building science) and they are likely to tell you “don’t build too tight, you want your house to breathe.” This is a tried and true “because that is the way we always do it idea.”



Early in the construction industry you did not build a home air-tight so that the walls could dry out. This is a leftover from days before we insulated or conditioned a home and wanted to air them out to keep them healthy inside.


However, now we have added insulation into our walls to increase energy performance.

Now we have heating, cooling, and ventilation systems to control indoor-air-quality and make the house comfortable and healthy.


So if your builder tells you they have done anything less than make your home as air tight as an igloo cooler, ask them if they will help pay your monthly electric bills. Ask them if they will come and dust your home once a week. Ask them why they continue to build as if the house is not insulated or conditioned.


Making your home air tight is key to a healthy, energy-efficient, and durable solution. Of course you do need a heating and cooling system that includes ventilation. This is how you bring fresh air into the house – through a filter – using an energy recovery ventilator. Making your home air tight filters the air reducing the need to dust. It also reduces energy consumption. It also filters the air improving indoor air quality. Making it air tight includes sealing every connection, joint, vent, penetration, window, door, roof, and hole.


Triple C Camp - NEST Rebuild, 2010