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.

Designing Healthier Homes by Eliminating Fossil Gas Appliance Emissions

Architects, as the primary designers of our built environment, hold a profoundly influential position in shaping the health and well-being of building occupants. Beyond the critical considerations of aesthetics, structural integrity, and energy performance, a deep understanding of the invisible forces at play within a building's envelope is increasingly paramount. This report aims to equip architects with the essential knowledge to proactively design for superior indoor air quality (IAQ), particularly concerning emissions from common household gas appliances. The decisions made during the design phase, from material selection to mechanical system integration, directly influence the indoor environment and, by extension, the health outcomes of those who inhabit these spaces. This effectively positions architects as critical guardians of public well-being within the built space, expanding their traditional role to encompass a vital public health responsibility.

Indoor Air Quality, HVAC, Electrification, Architectural Design, Building Enclosure, Code, Filtration, Healthy Home, High Performance Homes, VentilationPositive EnergyMay 22, 2025Designing healthier homes, eliminating fossil gas appliance emissions, indoor environmental quality, architect's role, indoor air quality, gas appliances impact on home health, combustion byproducts, hazardous air pollutants, synthesizing scientific findings, actionable strategies for architectural practice, pollutants emitted by gas appliances, health effects, design and engineering solutions, fundamentals of indoor air quality, source control, ventilation, filtration, temperature and relative humidity levels, building as a dynamic system, geographic site, local climate, physical structure, HVAC, construction techniques, contaminant sources, occupants' activities and behaviors, air exchange pathways, mechanical ventilation systems, infiltration, air pressure differences, building envelope, "Building Tight, Ventilate Right" imperative, energy consumption, pollutant concentration, energy efficiency, ventilation strategies, indoor air pollutants exceed outdoor levels, internal pollutant sources, "concentration trap", managing and removing internal contaminants, key pollutants from gas appliances, nitrogen dioxide, carbon monoxide, particulate matter, volatile organic compounds, moisture, respiratory irritation, asthma exacerbation, infection risk, decreased lung function, fatigue, chest pain, impaired vision, headaches, dizziness, confusion, nausea, DNA damage, mortality, transmission of airborne pathogens, organ damage, allergic reactions, cancer, dampness, mold growth, electric coil burners, high-dose exposure, pulmonary edema, diffuse lung injury, bronchitis, ambient air quality standards, carboxyhemoglobin, unvented gas space heaters, gas stoves, back-drafting, angia, poor ventilation, ultrafine particles, respirable particulate matter, cooking emissions, airborne particles, pathogens, respiratory aerosols, formaldehyde, benzene, unburned natural gas leakage, environmental tobacco smoke, automobile exhaust, sensory irritation, carcinogens, moisture load, human respiration and perspiration, bathing, washing, plants, pets, appliance selection, all-electric homes, electronic ignitions, proper appliance installation and maintenance, ducted range hoods, capture efficiency, airflow requirements, multi-family homes, whole-house ventilation strategies, tighter building envelopes, backdrafting risks, make-up air systems, targeted spot exhaust, bathroom fan, high-efficiency filtration, MERV-13, infectious aerosol exposure, cost-benefit analysis, air cleaning, indoor particle concentrations, semivolatile organic compounds, monitoring and alarms, carbon monoxide alarms, advanced IAQ monitors, PM2.5 sources, collaboration with MEP engineers, certified technicians, health impacts, continuous leakage, moisture byproduct, all-electric transition, building a healthier future, works cited, RMI, ASHRAE, EPA, LBNL, ventilation and air cleaning, envelope leakage, hazardous air pollutant emissions, residential ventilation requirements.

What Have We Learned About Air Conditioning & The Coronavirus

In an effort to broadly provide resources to our clientele and audience, we’ve written articles on the topics of health precautions for construction job sites and designing for healthy environments while reducing pathogen spread. We’ve released podcast episodes on the impact of ventilation and filtration on virus transmission. But now it’s time to talk about a serious elephant in the room as it pertains to coronavirus spread - air conditioning.

Indoor Air Quality, HVAC, COVID, Healthy Home, Filtration, VentilationPositive EnergyAugust 31, 2020SARS-CoV-2, COVID-19, Air Conditioning, Indoor Air Quality, Ventilation, Filtration, Masks, Humidity, Aerosols

State of the Art HVAC: Five keys to flawless space conditioning.

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