Occupant comfort and return on investment can be delivered by focusing on a better designed building envelope. One practice in particular provides significant building energy savings and durability while also improving occupant health and wellness. It’s called Quality Insulation Installation, or QII. Thermal comfort with improved efficiency is the fundamental goal when installing insulation. However, following the guidelines and practices outlined in the Quality Insulation Installation method optimizes the performance of the materials and reduces risks from other building wellness issues such as mold, pest and rodent debris, and air transfer between units that may include smoke or even biological contaminants such as airborne pathogens. For some occupants who may be immunocompromised or have lung deficiencies, these are significant risks.
QII is an elective performance measure involving a number of criteria with stringent requirements that must be verified by a HERS rater. This involves inspections for a continuous air barrier, continuous thermal barrier, and installation quality. Don’t let that scare you though: it’s a highly recommended program and is worth every bit of the extra effort. Through California-compliant energy modelling software, we have witnessed anywhere from 6-20% energy savings depending on the climate zone and building design by incorporating QII. Additionally, skipping QII under the 2019 Energy Code for low-rise residential buildings will result in an equivalent loss of savings since the measure is now prescriptive and heavily factors into most new compliant buildings now (i.e. making your building more expensive to operate and possibly not complying with minimum energy performance requirements if not taken by default).
In general, to pass QII, all installed insulation must completely fill the cavity in which it is being installed with a perfect friction fit to allow the insulation to have solid contact with an air barrier on all 6 sides. This means no voids, compressions, gaps, or dead air space within the wall system. Areas too small to insulate are filled with expanding foam. All air gaps between units and to the outside are also filled with expanding foam to limit air movement through the wall and to ensure no portions of the wall are left uninsulated. While it is obvious how this can drastically affect energy savings, the lesser known effects to health and wellness of the occupants may be just as big of a selling point.
Air sealing is one of the main portions of the QII program and consists of installing draft stops at all penetrations through the envelope and using expanding foam to fill in all cracks and gaps in the envelope. This will limit the amount of air being exfiltrated or infiltrated through the dwelling unit. From an energy efficiency standpoint, this is beneficial for reducing heating and cooling loads. However, this also has a significant impact on the air quality in the dwelling unit. By sealing the envelope, we can reduce the risk of outside contaminants coming into the living space passively through the small cracks and gaps that may exist through the wall system. This could be exhaust air from outside, dust, smoke from tenants in adjacent dwellings, or even airborne biological pathogens or mold spores, etc. All these particles can travel passively through a wall if even the smallest pathway exists for air to flow through it.
Air currents are also responsible for up to 98% of all water vapor movement in a home according to the Insulation Institute. This represents a huge risk toward mold growth in the home by allowing air from warm damp areas such as a bathroom to travel to colder areas and condense on building materials in adjacent rooms or in the attic. In California, mold (including black mold) is natural and commonly found. The World Health Organization for Europe estimated that around 50% of homes contained mold. However, the estimate is much higher for areas such as California where it is much more endemic and moderate temperatures create an ideal environment for its growth. Mold needs moisture, a substrate, and moderate temperatures making California beach homes perfect for mold growth and areas in the inland desert regions at much less risk.
As air drops in temperature, its ability to absorb moisture decreases. When hot air that is saturated with moisture, such as from a shower, travels to a colder environment, the air’s ability to hold moisture drops below what it’s already carrying and moisture will be deposited into that colder space. Even a very slight difference in temperature can make a drastic change to the moisture being dropped. Convective currents in the walls can be created from the warm bed of a sleeping person during a cold night. As the air moves in the wall it will condense moisture taken from warmer spots into colder areas creating an ideal environment for mold growth. Once spores make their way to one of these moist spots, it can grow and spread through materials and eventually put more back into the air. Mold spores have been known to cause a list of respiratory illnesses, and symptoms for chronic exposure can be quite severe. By reducing the risk of these air currents, we can reduce the risk of mold and improve the health of the dwelling.
Installation quality and material choice can greatly affect the performance of insulation. Certain materials such as cellulose are perfect substrates for mold compared to the fiberglass variety. Rigid and/or blown-in attic insulation is preferred as well to minimize small air gaps around framing that would otherwise not be filled or covered if batts were used.
Utilizing Forward Looking Infrared technology, we can see that a poorly installed fiberglass batt performs worse than a properly installed fiberglass batt. It’s easy to see from an energy efficiency standpoint that proper installation is necessary to optimize the performance of the material. It is the same from a health and wellness standpoint. The same gaps and spaces or areas of compression that need to be avoided to maximize performance must also be avoided to reduce risks to health of the occupants. Each of the areas of compression or gaps and air spaces in the insulation represent possible areas where convective air currents in the walls may flow, so installation quality is also a factor in air movement that could transfer contaminants or moisture between spaces.
In addition, these gaps and areas of compression represent pathways of travel for rodents and pests within the wall system. Each gap can create an uninhibited space where pests may dwell or easily move. Ensuring that the entire cavity within the wall is filled completely will reduce the risk of these pests being able to move freely or reside. Air sealing will also go a long way toward preventing them from getting in to begin with. The air sealing phase of QII will ensure that all gaps in the envelope are filled and sealed which will significantly reduce the amount of pathways into the dwelling units. Risks from pests are vast and can include extensive property damage as well as general respiratory illnesses to more severe diseases that can be transmitted from the pests themselves.
When considering QII for a new building, it is important to note that this measure is not only going to improve the dwelling’s energy performance, but it will improve building durability and improve the health and safety of the occupants. For more information on how to maximize your building’s insulation properties, contact Moe Fakih at VCA Green below.
Contributing Writer: Chris Halamandaris, HERS Rater
Moe Fakih, Principal