Indoor Air Quality - A Prerequisite to a Healthier Home
Since our inception, Dvele had the goal of providing a living experience for people that was modern, visually pleasing, and physiologically beneficial. Human health and wellness has always been one of the foundational cornerstones of Dvele. We strive to provide a home that positively impacts both the human body and the human spirit. There are many elements of this multifaceted discipline. The focus of this blog is on the building envelope (enclosure), indoor air quality, and water filtration.
Building Envelope / Enclosure
The building envelope is an area that is often neglected in the building industry. The building envelope is simply the parts of a building that are exposed to both indoor and outdoor ambient conditions. This includes the roof, exterior walls, doors & windows, foundation walls, and the crawl space slab. A properly designed and crafted building envelope can mitigate many potential building science-related issues, and is the only barrier between optimal human comfort and the outdoor conditions, whatever those happen to be on any given day.
As we all know, but sometimes neglect, as it relates to buildings, an object that is exposed to different environmental conditions simultaneously, can lead to conditions where bad things happen. Think of a cold aluminum can full of your favorite cold beverage on a hot summer day. If you respect the wood, you likely would place a coaster between the coffee table and the can as a barrier. Without a coaster under that can, one could leave a nasty ring on a wooden table that would upset some people. Imagine that same scenario in the walls of your home. On a cold winter day, a home with a traditional stud wall with fluffy insulation batts would have a dew point on the inside face of the exterior sheathing. Moisture inside your wall is not a good thing when the wall is a perfect food source for fungi to grow. Moisture in a building cavity is often not visible until there is a major problem. Those problems could be rot, decay, or mold. Neither of these things are something you want hiding in your walls. Dvele’s solution to mitigate this risk is what is known as continuous exterior insulation.
Insulation is often viewed as an energy efficiency measure, but it can also serve as a life extension for the building. The exterior insulation covers all of the walls from the top of footing to the soffit, where it meets the continuous exterior insulation that continues across the entire roof of the home. Under the crawl space slab, 2 layers of insulation provide the thermal break at the connection to the moist, cool earth. In the example of the walls, the continuous exterior insulation (CI) moves the dew point (when airborne water vapor is able to condense on a surface causing liquid water) location of the wall assembly outside the wall cavities of the home. This helps to minimize any risk of condensation inside that hidden wall cavity, and avoids that risk of mold, rot, and decay. This is just one illustration of how Dvele details, for how we build our walls and roof, have a direct health impact.
Mold exposure in a building has been shown to have major health effects for the building occupants. It is estimated that over 50% of buildings in the US have moisture-related building failures. Studies by Dr. Ritchie Shoemaker have shown that more than 24% of the US population are genetically predispositioned to having severe symptoms due to toxic mold exposure inside of a building. The symptoms can cause sickness, brain dysfunction, trigger auto-immune diseases, and weaken your immune system making you more susceptible to other viruses or bacteria. Living in a building in the US gives a person a pretty uncomfortably high risk of developing major health issues with this alone. That's why Dvele pays so much attention to the details within the building envelope. We can take that exposure risk out of the equation, and thus mitigate the risk of a triggering event.
Other Dvelian elements that support this are the fact that we manufacture our homes inside a controlled environment, the Foundry, where a rain event can not happen during construction that would soak the entire structure. The air control layer of our assembly and overall air tightness prevent large amounts of moisture laden air to come into contact with cold surfaces where condensation could occur. Dvele’s ventilated rainscreen, drainage gap between the siding and exterior insulation, breaks up any wind driven rain pressure that could drive water into a building and force that water to drain via gravity. Stainless steel flashings kick water away from any window, door, outlet, light, and foundation to protect the home from yet another place where water all too often enters traditionally built or existing homes. Contrary to commonly held belief in the California building industry that it does not rain enough to worry about these types of things, the evidence is clear that having such assurances against these water-related issues is more than comforting. And peace of mind comfort leads to another layer of emotional health.
(Above) Outside corner detail and inside corner detail shows continuous exterior insulation, liquid-applied air barrier, and stainless steel base wall flashings. This is Dvele’s standard system.
(Above) Exterior Insulation in a process over liquid-applied air control layer and waterproofing layer. The insulation also meets the liquid flashed, waterproofed window opening.
(Above) The Ventilated Rainscreen is ready for siding. The rainscreen is outward of the weather-resistant, radiant barrier over the continuous exterior insulation.
(Above) The joinery used in the foam panels on top of the roof gets applied over liquid applied membrane.
Dvele’s standard conditioned crawlspace creates a crawl space under the home that matches the integrity of the home. The crawl space is airtight, well insulated, and receives both heated/cooled air as well as fresh filtered air to keep condensation risk-controlled and air constantly moving throughout the space to prevent mustiness. Doesn’t it make sense to put your home on top of a foundation that was also engineered and produced properly? I guess only if the home was also built with integrity, as a Dvele home assures you of.
Indoor Air Quality
Indoor air quality is hugely important to the occupants of any building. Since Americans spend most of their time indoors, even during normal life, and air is the element our body consumes the most of, indoor air quality is critical in a health-promoting home. This all starts with controlling what we bring into the home - both the materials Dvele chooses to build with and what a building occupant brings into the home. Dvele layers in fresh air delivery systems as well as technology solutions that better inform occupants of both their own behavioral impact on IAQ and the building's actual performance.
Source control is limiting what you bring into the home to optimize the baseline indoor air quality. Limiting what is built into the home is the first course of action to increase air quality. Dvele sources low emitting products that exceed the building codes, even in California where those codes are the most stringent in the US. Low emitting products are those that have less chemical off-gassing, or VOCs (volatile organic compounds). VOC’s are that new car smell or new house smell which is really air with high concentrations of chemicals. There are product certifications where building products and furnishings are tested in a lab, and can receive a certification to varying levels of “off-gassing” performance. There are also a host of other websites and resources for product declarations where more information is available on a product. The best and easiest way of sourcing better products is for building material manufacturers to voluntarily disclose the ingredients (AKA chemicals) that are used in their products. Full ingredient transparency is the first filter we used when vetting products to integrate within our homes. Declare, by International Living Future Institute, is one such label that discloses what chemicals are in certain manufacturers' products...those with the highest level of integrity. Declare is the avenue ILFI provided so that manufacturers could make Living Building Challenge certification easier for project teams by disclosing chemical content upfront. Project teams have helped serve as a catalyst to a materials transparency revolution by collaborating with high integrity manufacturers to release this information for not only their project but all project teams. In 8 years, there are now hundreds of products with full transparency listed on the Declare website.
The full electrification of Dvele homes has energy efficiency advantages but also contributes to the increased health and safety of the homes. Without natural gas combustion in a home, there is no risk of carbon monoxide inside a Dvele home. In addition, having an induction cooktop versus a gas stove helps reduce harmful ultrafine particulates and gasses. Nitrogen oxides, a byproduct of cooking with gas, are known respiratory irritants. Natural gas cooking can create conditions inside the home that the EPA views as dangerous for even outdoor conditions.
Particulate matter is another area Dvele pays close attention to. Particulate matter, PM, is another term for dust. This starts again with source control beginning with our manufacturing process in the Foundry. Doing things like vacuuming out each and every stud bay before insulation removes dust from the construction process which leads to a less dusty home upon completion. All phases of manufacturing and site construction are important to ensure as little dust gets trapped in the house as possible. After occupancy, it becomes a matter of occupancy lifestyle and behavior as well as our ventilation system constantly cleaning the airborne particles out of the air within the home. Low hanging fruit for occupants to control the PM in their homes is simply taking off shoes upon entering the home. An in-home dashboard can display current PM levels to inform the residents of the home, but also can trigger specific functions within the ventilation system so occupants do not need to manually make those adjustments. This sensor to a dashboard to ventilation system communication also works for the VOCs noted previously as well as CO2. This is important because studies show that high PM2.5 exposure can cause chronic airway inflammation which lessens your bodies ability to fight biological contaminants and thus increase the risk of respiratory infections.* High PM2.5 can also cause your body to overcompensate the immune response and lead to allergies.
Proper ventilation of a home is critical to create a healthy environment. Proper ventilation means a fully distributed and balanced system with heat recovery. Dvele homes meet or exceed Passive House requirements of air tightness so they cannot rely upon leakage to provide “fresh air” as most homes do. They also can not reply upon exhaust only or supply only ventilation. The energy recovery ventilator, ERV, is the next line and continuous line of defense to keep healthy air quality, and picks up where source control leaves off. A study published last year found that just minimum levels of fresh air ventilation in a building reduced influenza transmission equal to that of having 50%-60% of building occupants vaccinated.
During the current COVID19 pandemic, medical professions have advised the public to increase fresh air into their building, and also increase exhaust air ventilation. Dvele incorporates a dedicated fresh air delivery system that tackles both of those items in an efficient way. This system provides fresh, twice filtered air throughout the living spaces of the home. It also extracts the same amount of air, measured in cfm, from those areas in the home that produce moisture and odors, the bathrooms, kitchen, and laundry room. Each room also has an acoustically dampened transfer grill to allow proper air circulation through the home. This also keeps pressure balanced throughout the home which creates a more comfortable environment.
In a Dvele home, the entire air volume of the homes is exchanged every 3 hours at most. Not only is the air exchanged, but that air exchange being controlled by a mechanical system that allows for all of that air to be highly filtered. As a standard, the ERV itself comes with two MERV 8 filters. However, in a Dvele, the fresh incoming air from outside first runs through a MERV 13 standard pre-filter, and is upgradeable from there. MERV 13 is used in some medical settings, and is a high-level filter for home environments. People can upgrade as desired for personal health reasons, or for local environmental risks Dvele can integrate a solution for. MERV 13 captures 90% of dust between 1-10 microns.
This fresh air delivery system also includes energy recovery. This means that the outgoing exhaust air stream preconditions the incoming fresh air stream. The air streams pass each other to transfer the energy, but are separated by a membrane so that there is no cross-contamination of the opposing air streams. This increases the energy efficiency of a home providing fresh air, but also ensures comfort. The fresh air is thus preconditioned close to the ambient temperatures in the home to also help it increase comfort.
The combination of a very tight building envelope, and a dedicated fresh air delivery system allow for Dvele homes to optimize the indoor environmental quality. When this system is coupled with Dvele’s proprietary smart home system, ROSIE, sensors report indoor air conditions to an in-home dashboard that can subsequently change settings within the ERV to improve air quality. These settings are preloaded so that no personal data needs to leave the home, unless a Dveler chooses to share.
Real-world performance is a critical function of a healthier home. This begins with actually measuring the air quality of a building. This is done with lab equipment post-construction and pre-occupancy. Once the home and all systems are quality checked, the continuous monitoring built into the home help to give continuous performance feedback to the occupants. This invaluable information provides many benefits to Dvelers.
Currently, most of us are still practicing shelter in place, and have been spending most of our time not only indoors, but in our own homes. Spending this much time in one place has left most of us becoming more aware of conditions within our homes. This has likely led to “I wish my home... “. We want you to interact with us and let us know what ideas or concepts you have wished was in your home. Click here to fill out a quick comment.
Dvele knows it can make a positive impact in the everyday life of its inhabitants. This has recently garnished more public attention as well. Recently, Joseph Allen, director Healthy Building Program at Harvard stated to the New York Times, “Limiting the impact of this epidemic will require an all-in approach. With significant uncertainty remaining we should be throwing everything we have at this highly infectious disease. That means unleashing the secret weapon in our arsenal - our buildings.”
Be safe, and stay healthy.
* “Inflammatory health effects of indoor and outdoor particulate matter” Dr Weidond Wu, Dr Yuefei Jin, & Dr. Chris Carlsten