Posts in Dehumidification

The Theresa Passive House: A Blueprint for High-Performance Design in Hot-Humid Climates

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.

Architectural Design, Building Enclosure, Building Science, Code, Dehumidification, Electrification, Environmental Design, Filtration, Healthy Home, Heat Pumps, High Performance Homes, HVAC, Indoor Air Quality, Mechanical Design, Passive House, Phius, Solar, VentilationPositive EnergyMay 28, 2025Theresa Passive House, high-performance design, hot-humid climates, residential performance, sustainable design, architectural preservation, energy efficiency, indoor air quality (IAQ), thermal comfort, embodied carbon, responsible materials sourcing, Passive House Institute U.S. (Phius), Phius certification, PHIUS 2018+ Source Zero, ASHRAE Climate Zone 2A, photovoltaic panels, battery backup systems, self-sufficiency, resilience, Forge Craft Architecture + Design, Hugh Jefferson Randolph Architects, Studio Ferme, integrated design process, building envelope, HVAC system, on-site solar panels, MEP (Mechanical, Electrical, Plumbing) engineering, Positive Energy, building science, human-centered design, net-zero energy buildings, heating loads, cooling loads, source energy, airtightness, energy modeling, continuous insulation, thermal bridges, air changes per hour (ACH@50 Pa), air leakage, Blower Door Test, high-performance windows, triple-glazing, low-emissivity (low-e) coatings, Solar Heat Gain Coefficient (SHGC), balanced ventilation, Energy Recovery Ventilators (ERVs), dedicated dehumidification, right-sizing mechanical systems, comfort, health, durability, passive survivability, Winter Storm Uri, University of Texas research, climate-specific standards, moisture management, key performance metrics, site energy use index (EUI), renewable energy production, wall assemblies, water control layer, air control layer, thermal control layer, vapor control layer, wood frame system, mineral wool insulation, unvented roof, Marvin windows, indoor pollutants, combustion products, Volatile Organic Compounds (VOCs), particulate matter (PM2.5), ASHRAE Standard 62.2, ventilation rates, Variable Refrigerant Flow (VRF) heat pump AC, Panasonic Intellibalance 1000 ERV, MERV filtration, heat pump hot water heater, climate resilience, extreme weather events, grid outages, source zero certification, community education, AIA Housing Award, Passive Project of the Year – Retrofit, Austin Green Awards, affordable multifamily housing, building envelope prioritization, mechanical ventilation with energy recovery (ERV) implementation, MEP systems integration, advanced air filtration, MERV ratings, active energy independence, photovoltaics, battery storage, MEP engineer collaboration, climate-specific MEP solutions, commissioning agent

The 5 Principles of a Healthy Home

This blog post will present a foundational framework for architectural practice, emphasizing the profound impact of building design decisions on human health and well-being. Moving beyond conventional priorities of aesthetics and initial construction costs, which are unfortunately all too common and mundane in our modern era, this post introduces and explores "5 Principles of a Healthy Home." These principles offer a holistic approach to achieving superior indoor environmental quality (IEQ) and long-term building durability. By understanding and integrating these foundational building science concepts, architects are empowered to design spaces that actively promote the health, cognitive function, and restorative sleep of occupants, thereby elevating their role to advocates for human thriving.

Architectural Design, Building Enclosure, Building Science, Dehumidification, Filtration, Healthy Home, High Performance Homes, HVAC, Indoor Air Quality, Mechanical Design, VentilationPositive EnergyMay 27, 2025Building design and human health, indoor environmental quality (IEQ), principles of a healthy home, architects as advocates for human thriving, aesthetics vs. first cost in construction, indoor air quality, structural resilience, occupant well-being, human thriving, time spent indoors, invisible threats in indoor environments, particles, gas-phase pollutants, bioaerosols, physiological functions, cognitive functions, epigenetic changes, prenatal gene regulation, indoor air pollutants and gene expression, impact of air quality on cognitive abilities, decision-making, CO2 levels and cognitive performance, impact of air quality on sleep, particulate matter and nitrogen dioxide, sleep disturbances, building enclosure, moisture transport, water management, deflect, drain, dry principles, water-resistive barrier (WRB), flashing details, air barrier, insulation layer, vapor barrier, air leakage, air movement and water vapor transport, material selection and indoor air quality, toxic air pollutants, flame retardants, formaldehyde, chromated copper arsenate (CCA), lead, polyvinyl chloride (PVC), phthalates, dioxins, isocyanates, crystalline silica, air distribution system, flex duct, duct board, fluid dynamics, metal ductwork, air mixing, pollutant removal, indoor pollutants: particles, gases, particulate matter (PM), PM2.5, PM10, ultrafine particles, volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), bioaerosols: bacteria, viruses, protozoa, fungal spores, archaea, dust mites, active sources of indoor pollutants, cooking, showering, indoor combustion, air fresheners, personal care products, passive emissions, plasticizers, perfluorinated chemicals (PFAS), antimicrobials, six classes of harmful chemicals, dust as a pollutant reservoir, ventilation vs. air leakage, exhausting pollutants, supplying fresh air, ASHRAE Standard 62.1, ASHRAE 62.2, local exhaust: kitchen and bathroom, range hood, CFM (cubic feet per minute), whole-building fresh air, heat recovery ventilators (HRVs), energy recovery ventilators (ERVs), humidity control, excess moisture, mold growth, dimensional instability, VOC emissions, damp environments and health impacts, respiratory issues, 40-60% RH range, energy codes and latent loads, dehumidification needs, vapor compression dehumidifiers, desiccant dehumidifiers, particulate matter filtration, MERV ratings, HEPA filters, active air cleaning technologies, ozone, mechanical filtration.

The Case for Dedicated Dehumidification In Sealed Attics

Modern 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.

Building Science, Architectural Design, Building Enclosure, Dehumidification, Healthy Home, Filtration, High Performance Homes, HVAC, Indoor Air Quality, Mechanical DesignPositive EnergyMay 23, 2025Sealed attics, dedicated dehumidification, moisture control, energy efficiency, indoor air quality, HVAC systems, air leakage, building durability, condensation risks, mold growth, air barrier, thermal barrier, insulation, roof deck temperature, building codes (IRC), ASHRAE standards, unconditioned attics, conditioned attics, psychrometrics, vapor control, duct performance, latent load, sensible load, building science principles, dew point, hygric buffering, controlled ventilation, air sealing, maintenance issues, cross-contamination, volatile organic compounds (VOCs), pests, allergens, duct leakage, system strain, pressure balancing, wood framing, sheathing, building envelope, resilience, sustainability, dehumidifier sizing, condensate management, building science experts, MEP engineering.

Understanding "Ping Pong Water" and Navigating Attic Moisture Dynamics in Modern Roof Assemblies

The 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]

Building Enclosure, Building Science, Dehumidification, HVAC, High Performance Homes, Healthy Home, Code, Architectural DesignPositive EnergyMay 23, 2025"Ping Pong Water" phenomenon, attic moisture dynamics, modern roof assemblies, unvented attics, conditioned attics, moisture control challenges, roof sheathing moisture, attic ventilation, airtightness, energy efficiency, solar radiation, thermal buoyancy, hygric buoyancy, OSB hygroscopicity, chemical potential of wood, sorption isotherms, hysteresis, OSB and mold susceptibility, roof assembly durability risks, sheathing degradation, rot, corrosion of metal components, "bound water, " climate zone dependence, spray polyurethane foam (SPF), open-cell SPF (ocSPF), closed-cell SPF (ccSPF), vapor permeability, air barrier qualities, water barrier, code requirements, active attic conditioning, supply air strategies, return air strategies, dedicated dehumidification, exterior insulation, vapor diffusion ridge vents, fibrous insulation assemblies, cellulose, fiberglass, mineral wool, air tightness, vapor control layer, hybrid insulation systems, architect design considerations, building science principles, interior humidity management, material compatibility, constructability, quality control, building codes, hygrothermal modeling, risk management, lifecycle costs.

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