Sustainable Building Strategies
Enhancing your building practices can optimize energy efficiency and comfort while protecting structures from moisture and environmental stressors
Sustainable building practices revolve around the intersection of physics, architectural design and high-performance materials. Important concepts characterize these strategies such as energy efficiency, green building certifications, building resilience, durability and functionality. These approaches not only elevate a home’s visual appeal but also support long-term comfort, efficiency and livability.
In sustainable building design, understanding how moisture behaves is essential to creating durable, healthy and energy-efficient structures. The principles governing moisture movement are rooted in the three laws of thermodynamics, which directly influence construction strategies and material choices. Moisture will always migrate from wet to dry surfaces, from areas of high pressure to low pressure and from warm to cooler surfaces. By applying these fundamental principles, builders and designers create and construct buildings that can better manage moisture control, reducing the risk of damage and enhancing the overall performance of the sustainable elements.
Another essential component of sustainable building strategies is to recognize the “DNA” of green building. According to Chris Prelitz, a Custom Green Home Builder based in Laguna Beach, “DOIVM” is the essential DNA which includes, daylighting, orientation, insulation, ventilation and mass.
Daylighting brings light and warmth into a building, and the performance is influenced by solar radiation, window manufacturing, solar control coatings and building designs. The goal is to maximize visible light transmittance and minimize infrared heat energy and this is the role of various solar control coatings. The metrics of window performance include visible light transmittance and the solar heat gain coefficient both of which drive solar transmission. The choice of solar control coatings vary with the building location and micro-climate. The visible light range span (380-780 NM) across the solar radiation spectrum is only 42% of the total with non-visible ranges on either side. Shorter wavelength ultraviolet rays (300-380 NM) make up five percent and longer wavelength infrared radiation (780+ NM) is the bulk at 53%, which is the primary source of outside building heat from the sun.
Orientation is siting and positioning a building with the shortest dimension north/south, and the longest dimension east/west. This provides the best layout for maximizing energy efficiency. Then, wide horizontal eave overhangs on the south side (in the northern hemisphere) can be configured to protect windows from high intense summer solar radiation yet allow deep penetration of low winter sun into the building’s core. Light shelves inside and outside also contribute to building envelopes’ energy efficiency performance.
Insulation of the building envelope is critical for minimizing operational energy within dwellings. Air sealing achieves a tight building envelope which creates a more efficient enclosure. “The Perfect Wall” design by Dr. Joe Lstiburek adds four control layers to maximize effectiveness. These include the rain control layer (with rain screens where climate conditions require), thermal control layer (placed outside of the structural frame to minimize thermal bridging), air control layer and the vapor control layer, both of which prevent unwanted moisture from accumulating inside wall cavities and the living spaces.
Ventilation drives indoor air quality and health outcomes for many occupants. This includes both active (mechanical) and passive ventilation strategies, which can provide conditioned (dehumidified) fresh air from the outside. Interior wall treatments can also influence occupant comfort. American Clay Plaster, for example, has buffering qualities which absorbs and releases interior moisture, thus helping to stabilize inside humidity levels and improving indoor air quality.
Lastly, mass in a building’s foundation, and some building envelope components can provide passive energy “heat sinks” collecting long wave infrared radiation during the day and radiating back at night in the form of heat into the conditioned space.
High performance materials which have bio-mimicry characteristics are at the forefront of building science and sustainable design practices. These material science innovations which mimic processes in the natural world will continue to evolve. Monitoring and testing are important processes to verify building performance and are essential to document the effectiveness of these various sustainable design strategies. One must also compare outcomes to baseline conditions of traditional designs. Example testing equipment includes blower doors to pressurize or depressurize a home, theatrical smoke generators to track air leakage and HVAC flow hoods to determine internal air flow conditions. Infrared cameras also help identify cold spots from missing or inadequate insulation in a building envelope and water leaks in wall cavities.
Now, what’s in your toolbox?
By Don Neff. Don Neff is President/CEO of LJP Construction Services.
This article was featured in our September issue.
