Indoor environmental quality (IEQ), encompassing thermal comfort, acoustics, lighting and air, plays a vital role in shaping our health and wellbeing. Thermal comfort, a key component marked by temperature, humidity and airflow has a direct bearing on sleep, mood and focus. This comfort is highly personalized, influenced by individual factors such as clothing, activities, age and metabolic rate. In homes, varying temperatures in different areas arise from their specific use, time of day and seasonal changes. Many studies on thermal comfort have focused on office settings due to the direct correlation with productivity. Yet, the question remains: how does this translate to our homes?

Temperature and Health:

The World Health Organization advises that maintaining the right temperature at home is crucial for health. In colder climates, a minimum indoor temperature of 64.4°F (18°C) is recommended to safeguard residents during the colder seasons. Extreme cold can lead to cardiovascular and respiratory illnesses, while excessive heat may adversely affect mental health. Different rooms may require different temperatures; however, keeping your overall home within a range of approximately 67 to 82°F (19 to 27°C), as recommended by ASHRAE (The American Society of Heating, Refrigerating and Air-Conditioning Engineers), can help prevent these health issues and promote wellbeing.

Maintaining Thermal Neutrality:

Our bodies constantly strive to maintain a steady internal temperature of around 98.6°F (37°C), a process that can be strenuous when it’s excessively hot or cold. For comfortable living, a range of factors must be considered: humidity, air speed, air temperature, radiant temperature, metabolic rate and clothing insulation.

Maintaining the air’s moisture level between 40-60% is key; ASHRAE recommends keeping it under 65% to prevent mold and mildew. The sensation of air changes with its speed; a gentle breeze may be refreshing, while a strong draft could prompt us to reach for a sweater. Room temperature is also crucial. Biologically, we’re designed to cool down when it's above 80.6°F (27°C) and to retain heat below 64.4°F (18°C). Radiant temperature, emanating from heated objects like a sun-warmed chair, can significantly increase our sense of warmth. Our metabolic rate influences this as well; a higher rate increases heat production, impacting how we interact with our environment. The choice of clothing also plays a role in thermal comfort, with different materials and weaves offering varying levels of insulation. By managing these elements effectively, we can ensure optimal thermal comfort.

Thermal Comfort Strategies:

Effective home temperature management takes a holistic approach that goes beyond simply adjusting the air temperature. It involves strategies that address both radiant heat and humidity to ensure comfort and energy conservation. Programmable thermostats and smart systems are excellent for customizing your home’s climate efficiently. Additionally, addressing drafts and improving insulation are vital for keeping temperatures consistent and minimizing energy loss.

Regarding radiant heat, incorporating materials such as stone or brick into your home's architecture allows these elements to absorb heat during the day and release it slowly as temperatures drop. This offers a natural way of regulating temperature without relying solely on mechanical systems. For humidity, proper ventilation is key. Utilizing dehumidifiers in moist areas and incorporating houseplants that absorb humidity can aid in maintaining comfortable levels. Clay plaster wall treatments also contribute to regulating humidity naturally, promoting a balanced indoor climate.

Furthermore, selecting heavier curtains or blinds made from natural, certified fabrics—like those with GOTS, OEKO-TEX, or Greenguard Certifications—enhances insulation and improves air quality by limiting the off-gassing of chemicals common in synthetic alternatives. However, it's crucial to ensure adequate ventilation to prevent condensation buildup behind window treatments. Another solution that complements these interior strategies is integrating natural landscaping. Planting deciduous trees, for example, provides shade during the warmer months and allows sunlight to warm the home in the colder months, offering an effective form of thermal regulation that harmonizes your home’s climate with seasonal changes.

Each room in your home can benefit from specific temperature settings that correspond to its usage, optimizing both comfort and efficiency.

Bedrooms:

For adults, a cooler environment for sleeping, ideally between 60-68°F (15.6-20°C), corresponds with the body's natural cooling during the night, fostering a deeper state of rest. Overly warm rooms can disturb sleep, causing restlessness and dehydration, which impairs the body’s heat regulation and can lead to fatigue. Babies' and young children's bedrooms should be kept warmer, around 68-72°F (20-22.2°C).

• Choose breathable bedding, opting for natural fibers like cotton or linen for improved air circulation and temperature control. Add layers to maintain comfort throughout the night.
• Promote air circulation with an open window or a quiet fan.
• Use a dehumidifier or a humidifier to keep humidity at a comfortable level.
• Darkening curtains or blinds can help keep the room cool during the hotter months, but be mindful of their materials, as many full blackout ones are made from synthetic materials that can emit noxious gasses, reducing air quality within the room.
• Ensure proper ventilation, especially when using darkening curtains, by slightly opening windows or incorporating air-purifying plants to maintain air quality.

Living Areas:

In living spaces, temperatures around 68-71.6°F (20-22°C) can create an inviting atmosphere for relaxation and socializing.

• Use dimmers or adjustable LED lighting fixtures to create a warm ambiance without overheating the space.
• Layer textiles, using throw blankets or area rugs to adjust individual comfort without altering the room's temperature.
• Consider the placement of furniture to take advantage of natural radiant heat from windows in the winter, while using drapes or shades in the summer to minimize heat absorption.

Home Offices:

The temperature in your home office is key to maintaining focus. Cognitive performance tends to peak at a comfortable 71.6°F (22°C), making temperature control in your workspace essential. Extremes in temperature can be distracting and may lead to a decline in productivity.

• Adjustable window treatments can help manage natural light and minimize screen glare, contributing to both visual comfort and temperature regulation.
• Small, personal comfort devices such as a heated blanket or desk fan can provide immediate comfort without changing the overall temperature of the whole room.
• Place your desk near a source of natural light to benefit from radiant warmth during colder months, while having the option to shade the window to stay cool when it’s warmer.
• Manage humidity with indoor plants that can absorb excess moisture, or a small dehumidifier to keep the air comfortable for enhanced concentration.

Kitchens:

An ideal kitchen temperature is between 64.4-68°F (18-20°C), accommodating the heat fluctuations from cooking which can enhance the enjoyment of cooking and dining.

• Activate exhaust fans when cooking to remove excess heat.
• Ensure proper ventilation to manage both temperature and humidity, which can rise quickly during cooking or dishwashing.
• Consider using smaller appliances where possible such as slow cookers or air fryers instead of the oven.
• Open windows for cross-ventilation to prevent the kitchen from overheating during meal prep.
• Use materials like natural stone and tiles for floors or backsplashes to help stabilize the room temperature.

Bathrooms:

Bathrooms should be slightly warmer than the rest of the home, at 71.6-75˚F (22-24°C), to ensure comfort during bathing and grooming routines. Proper temperature and humidity levels prevent the growth of mold and mildew, which can have negative health implications.

• Always use ventilation fans during and after showers to expel humidity and maintain a comfortable temperature, reducing the risk of mold.
• Moderate water temperature as excessively hot showers can overheat the room and increase humidity levels.
• Install heated towel rails to provide warmth and aid in drying towels to prevent dampness.
• Consider radiant floor heating for consistent warmth that prevents the discomfort of cold tiles.

Photography: Katrine Rohrberg, Rich Stapleton, Felix Speller, Armadillo, Nainoa Architecture, César Béjar