Posts tagged air leakage

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.

Navigating the HVAC Refrigerant Transition and the Promise of Hydronic Systems for Future-Ready Architecture

The global heating, ventilation, and air conditioning (HVAC) industry is undergoing a significant transformation driven by the phasedown of high-Global Warming Potential (GWP) refrigerants, primarily Hydrofluorocarbons (HFCs). This shift, mandated by international agreements like the Kigali Amendment and domestic legislation such as the U.S. American Innovation and Manufacturing (AIM) Act, presents both substantial challenges and unique opportunities for the Architecture, Engineering, and Construction (AEC) industry.

Heat Pumps, HVAC, High Performance Homes, Indoor Air Quality, Electrification, Building Enclosure, Architectural Design, CodePositive EnergyMay 22, 2025HVAC refrigerant transition, high-Global Warming Potential (GWP) refrigerants, Hydrofluorocarbons (HFCs), Kigali Amendment, U.S. American Innovation and Manufacturing (AIM) Act, supply chain disruptions, refrigerant costs, technical training, mildly flammable refrigerants, hydronic systems, air-to-water heat pumps, ground source heat pumps, water as heat transfer medium, building performance, global HVAC refrigerant landscape, Montreal Protocol, ozone-depleting substances (ODS), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), HFC phasedown, U.S. ratification of Kigali Amendment, HFC consumption reduction, global warming mitigation, low-GWP technologies, HFC Allocation Program, Allocation Framework Rule, GWP limit of 700, R-410A systems, refrigerant leak detection, refrigerant reuse, reclaimed and recycled HFCs, leak repair, recordkeeping, reporting, labeling, automatic leak detection (ALD) systems, reclaimed HFCs for servicing, cost of compliance, A2L-class refrigerants, R-454B, R-32, refrigerant flammability, safety protocols, certified HVAC technicians, ACCA A2L training, ASHRAE Standards, UL Safety Standards, refrigerant types comparison, R-22, R-290 (Propane), R-744 (CO2), R-717 (Ammonia), AEC industry challenges, project timelines, supply chain constraints, refrigerant shortages, material scarcity, A2L safety training, regulatory compliance and enforcement, EPA regulations, state-level regulations, equipment availability and compatibility, refrigerant recovery machines, hydronic system types, radiant systems, baseboard heating, chilled beam systems, snow melt systems, AWHPs principles, AWHPs benefits, GSHPs principles, GSHPs advantages, ground loop, ground temperature stability, GSHP design considerations, GSHP energy savings, Investment Tax Credit (ITC), Inflation Reduction Act (IRA), technology neutral homes, renewable electricity sources, building envelope performance, HVAC system sizing, thermal insulation, high-performance glazing, air leakage, whole building design, commissioning, thermal performance, airtightness, passive building principles, Phius (Passive House Institute US), continuous insulation, thermal bridging, condensation prevention, super-insulation, minimal space conditioning system, moisture management, dew point temperature, latent loads, dedicated outdoor air system (DOAS), dehumidification, smart controls, material selection for radiant cooling, wall design for hydronics, floor design for hydronics, ceiling design for hydronics, building physics, heat transfer processes, moisture dynamics, indoor air quality, economic benefits of hydronic systems, operational cost reductions, energy efficiency, high-efficiency circulator, VRF system comparison, DX unit comparison, water source heat pumps, lifespan of hydronic systems, maintenance costs, environmental impact of hydronics, decarbonization, solar thermal, geothermal energy, strategic design for sustainable HVAC.

Rethinking Moisture Control: The Primacy of Air Tightness Over an Outdated Fixation on Vapor Barriers in Building Envelope Design

For 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.

Building EnclosurePositive EnergyMay 22, 2025Vapor Barriers, Air Barriers, Building Envelope, Building Science, Moisture Management, Dehumidification, Durability, Resiliency, Air tightness, vapor barriers, moisture control, building envelope design, moisture transport mechanisms, air leakage, vapor diffusion, air barrier systems, historical context of vapor barriers, evolution of vapor barrier science, bulk water intrusion, capillary action, air-transported moisture, defining air barriers, defining vapor retarders, air permeance, water vapor permeance, dew point temperature, energy efficiency, indoor air quality, building durability, acoustic control, continuity of air barrier, dedicated dehumidification, climate-specific vapor control, reservoir claddings, solar-driven inward vapor drive, ventilated rainscreen, "smart" vapor retarders, moving forward with air tightness, recommendations for architecture and construction, building codes and standards, quality assurance/quality control

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