The Theresa Passive House, nestled in Austin's historic Clarksville neighborhood, stands as a remarkable example of how architectural preservation can harmoniously merge with modern sustainable design. This 2100 square foot residence, completed in 2020, is not merely a renovation and addition to a 1914 Craftsman bungalow; it is a meticulously engineered dwelling that embodies rigorous targets in energy efficiency, indoor air quality (IAQ), thermal comfort, embodied carbon, and responsible materials sourcing.[1] These ambitious goals were established by the Passive House Institute U.S. (Phius), a leading authority in high-performance building standards.
Read MoreModern building design increasingly embraces sealed attic construction as a strategy to enhance energy efficiency and improve air leakage control, particularly beneficial for the performance of HVAC ductwork. This approach, where the attic space is brought within the building's thermal and air control envelope, fundamentally alters the moisture dynamics compared to traditional vented attics. While offering significant advantages, sealed attics introduce unique moisture challenges that demand precise and active management to prevent long-term durability issues and maintain superior indoor air quality.
Read MoreThe design of residential attics has undergone a significant transformation. Conventionally, attics were vented spaces with thermal insulation placed on the attic floor, separating the unconditioned attic from the conditioned living space below. However, contemporary building practices increasingly favor unvented, or "conditioned," attics where insulation is applied directly to the underside of the roof deck.[1] This shift is driven by several factors, including the desire to bring HVAC equipment and ductwork within the building's thermal and air barrier envelope to improve system efficiency and longevity, enhance overall building airtightness for energy savings, and create potentially usable conditioned or semi-conditioned space within the attic volume.[3]
Read MoreFor decades, the architecture and construction community has engaged in a persistent debate surrounding the role and necessity of vapor barriers in building envelope design. This discussion, while touching on critical aspects of moisture control, has often been characterized by an overemphasis on the ability of specific materials to resist vapor diffusion, sometimes to the detriment of addressing more significant moisture transport mechanisms. Within the building science community, however, the principles governing moisture movement are largely considered settled science. It is well-established that air leakage, rather than vapor diffusion, is the predominant pathway for moisture transport through most wall assemblies.
Read MoreThe promise of a new home often includes visions of a healthier, more energy-efficient living space. However, a subtle yet significant regulatory shift in U.S. building codes, particularly affecting hot-humid climate zones, may be inadvertently undermining this very promise. Before 2021, residential ventilation requirements were often loosely enforced; homes were typically required to have a ventilator, but the actual volume of air exchanged was not mandated to be measured. This frequently led to systems being ineffectively installed or even "sabotaged" by HVAC contractors, rendering them inoperable or improperly configured from the outset. Consequently, many homes, even in that period, did not achieve consistent fresh air exchange. Compounding this, most residential HVAC systems lacked any form of supplemental or dedicated dehumidification, a feature that building science experts have increasingly recognized as crucial, especially for high-performance homes in moisture-laden environments.
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