Design

When most people think about climate change, they picture smokestacks, traffic jams, or oil rigs. But one of the most significant contributors to global carbon emissions is much closer to home—literally. It is the buildings where we live, work, and learn.

From cozy homes and bustling offices to low-slung schools and towering apartment blocks, buildings are responsible for a substantial share of carbon emissions, not just during construction, but from every single day of use. According to the UN Environment Programme (UNEP) report, which uses data from the International Energy Agency (IEA), the buildings and construction sector together accounted for 34% of all energy-related global CO2 emissions and over 32% of global energy demand in 2023.

So, where does all that CO2 come from?

A building’s carbon footprint has two main sources—one before you ever step inside, and one that continues throughout its life: Embodied Carbon and Operational Carbon.

What is Embodied Carbon?

Emissions are generated by the production, transport, and installation of materials like concrete, steel, bricks, plastic, and glass—all before the building is ever used. This is known as Embodied Carbon (EC). It refers to the emissions associated with how the building is constructed, rather than how it is used (World Green Building Council, 2019). 

What is Operational Carbon?

Once buildings are utilized, they generate emissions from everyday energy use, mainly for heating, cooling, lighting, and operating appliances or equipment. These ongoing emissions are known as Operational Carbon (OC) (UKGBC, 2025). Figure 1 below illustrates how both EC and  OC contribute to a building’s total emissions across its life cycle.

Figure 1: Carbon Emissions in Buildings

Diagram by Sustainable Facilities Tool (SFTool) – U.S. General Services Administration (GSA)

However, even before we get to materials or energy use, we need to consider design, because how a building is positioned and shaped, from its orientation to earth-sheltered layouts, as well as its shading, cross-ventilation, and use of natural daylighting, can dramatically reduce its energy needs.

And here’s the good news: you don’t need to be an architect or a policy expert to make a difference. Whether you are building a new home, renovating your current space with different materials, advocating for better design in your community, or simply sealing up a drafty window, every step counts. Every home, office, and school is part of the climate story—and that means they are part of the solution, too.

1. Design Comes First

In any home or building project, the journey begins with essential design decisions, such as how the structure is oriented toward the sun, where windows are placed, and how air will flow through the space. These early choices significantly affect a building’s long-term energy use, comfort, and costs.

But how exactly does this work?

This is where passive design comes in. Passive design uses a building’s natural surroundings—such as sunlight, breezes, shade, and thermal mass—to naturally light, heat, and cool the space with minimal energy consumption. Instead of depending heavily on mechanical systems like space heaters or air conditioners, passive strategies work with natural elements to achieve comfortable and efficient living and working environments. In fact, homes that use passive design in Europe have been shown to use up to 90% less energy for heating (International Passive House Association, n.d.) than regular buildings, while passive cooling techniques like shade and natural ventilation can reduce air-conditioning use by up to 80% (University of Oregon, 2022).

While the most effective techniques often depend on local climate, seasonal temperatures, and even the shape and layout of the land, passive design offers flexible solutions that adapt to the environment to support energy efficiency and comfort throughout the year. Below are several proven strategies you can consider, whether you are designing a new building, remodeling, or looking to improve the comfort and energy efficiency of your current home.

  ★ Building Orientation:

Positioning a building to maximize solar gain during colder seasons and to minimize it during hotter ones can lower your heating and cooling needs (sometimes significantly)—something many of us instinctively understand but do not always plan for. For example, in colder climates, studies show that properly oriented homes can decrease heating energy use by 10–20%, and in some cases up to 40% by orienting windows toward the south in the Northern Hemisphere (or north in the Southern Hemisphere) to increase heat gain and limit wind exposure (InterNACHI, n.d.).

In warmer climates, a bit of thoughtful planning and shading helps you limit excessive sun exposure during the hottest parts of the day, thereby reducing reliance on energy-intensive systems such as air conditioners and mechanical ventilators. In fact, air conditioning accounts for about 19% of residential electricity use in the U.S. (EIA, 2023). A 2024 study using energy simulation found that optimizing building orientation alone can reduce overall energy use by an average of 18%.

So, for a typical 2,000-square-foot home, that means roughly 360 kilowatt-hours of electricity saved each year, which is equivalent to about $54 in utility costs or 306 pounds of carbon emissions. While that may seem modest for one home, these savings add up quickly when applied across neighborhoods, cities, or entire new developments.

Figure 2 illustrates how our choice of orientation affects the amount of sunlight and warmth a building receives throughout the year. This helps balance comfort and energy use without depending overly much on mechanical systems. It is a simple reminder that nature, when used wisely, can be one of the most powerful tools in building design.

Figure 2: Building Orientation for Sunlight and Natural Ventilation

Diagram by U.S. Department of Energy

Orientation, however, is not just about sun exposure. As Figure 3 shows, buildings that share walls—like row homes or duplexes—hold onto heat better in winter and resist overheating in summer, since fewer sides are exposed to outdoor temperature swings. That is essentially free insulation built right into the design. And the difference it makes is massive: according to the U.S. Energy Information Administration (EIA), the average household in a single-family, detached home consumes nearly three times more energy than a household in a multifamily building with five or more units, meaning that attached or shared-wall homes use around 66% less energy. That is lower bills, more comfort year-round, and fewer emissions, all without lifting a finger once the house is built.

Figure 3: Row Homes That Share Walls Reduce Heat Loss And Maintain Indoor Temperatures More Efficiently

Image by Curtis Adams via Pexels.com

  ★ Earth-Sheltered Homes:

But smart design does not stop with orientation. Want an even more grounded idea? Try building into the earth—literally. These are called earth-sheltered homes (or underground homes), as shown in Figure 4.

Figure 4: Earth-Sheltered Home Built into a Hillside for Natural Insulation

Image by Freysteinn G. Jonsson via Unsplash.com

These homes, which are partially embedded in hillsides or covered with soil, make the most of the ground’s natural insulation. According to the U.S. Department of Energy, they are far less affected by extreme outdoor temperatures and can dramatically lower heating and cooling needs—especially in places with big seasonal swings—thanks to the natural protection from wind and temperature fluctuations. That can translate to serious savings, with some estimates showing savings of 60–85% on heating and cooling costs. And think about how cozy basements feel in winter and how nice and cool they are in summer—that is the earth working like a comfy blanket, keeping things just right all year round. Pretty cool, right?

  ★ Shading:

Shading is another key passive design strategy. Properly designed shading devices—like overhangs, awnings, or even vegetation—help regulate when and how sunlight enters a building. While orientation determines overall sun exposure, shading controls when and how that sunlight enters, effectively managing glare, heat, and light throughout the day. These devices can be static, such as fixed overhangs that block high summer sun while allowing lower winter sun in, or dynamic, such as adjustable awnings or movable screens that respond to changing conditions.

Figure 5: Shading Examples

Image by Vu Anh via Unsplash.com

Image by Magda Ehlers via Pexels.com

By reducing heat gain when it is not needed, shading helps maintain comfortable indoor temperatures and can cut energy use by over 60% in some hot, sunny climates, especially from cooling systems, according to a study by Pérez-Carramiñana et al. (2024) from the University of Alicante. In this way, thoughtful shading design becomes a simple yet powerful tool for improving a building’s energy performance while promoting sustainability.

  ★ Cross-ventilation:

Another important passive cooling strategy is cross-ventilation, which encourages natural airflow within buildings. By strategically designing openings and interior layouts, buildings can improve indoor air quality while reducing reliance on air conditioners, electric fans, or mechanical ventilation systems. According to a 2022 study by Gil-Ozoudeh et al. at Enugu State University of Science and Technology, buildings with effective natural ventilation systems can reduce cooling energy consumption by up to 40%. That’s a big deal—not just for your energy bill, but also for creating a breezier, healthier space to live or work in. And let’s be honest—who wouldn’t welcome that cooling breeze, especially on those scorching days and nights?

Key Factors for Effective Cross Ventilation

• Interior volume: Open interior spaces allow air to flow more freely through the building.
• System sizing: Openings must be appropriately sized to ensure sufficient airflow. According to WindowMaster (2024), achieving effective natural ventilation typically requires openings equal to around 2% of the floor area in cross-ventilation and up to 6% in a single-sided setup.
• Air pressure performance: Effective design ensures a consistent turnover of fresh air to maintain healthy indoor air quality.
• Air exchange rates: The layout should prevent stagnant air and support steady circulation.

Figure 6 below shows how strategically positioned windows allow cool air to enter through low openings and push warm air out through higher vents, enhancing airflow and limiting the need for air conditioning and other powered cooling systems.

Figure 6: Cross-Ventilation in Passive Building Design

Image courtesy of Hugh Holder / Architropics.com 

While some of the strategies above may require the help of a designer or architect, others are surprisingly simple. For example, opening lower windows on one side of your home and upper windows on the opposite, downwind side can significantly improve airflow. By prioritizing cross-ventilation, you can create a healthier and more comfortable home while reducing your energy consumption.

  ★ Natural Daylighting:

Natural daylighting focuses on how light is brought inside and used effectively. This practice is increasingly recognized as a fundamental aspect of sustainable building design because it minimizes the use of artificial lighting, improves visual comfort, and enhances overall well-being, as highlighted by Arkar Htet et al. in their 2023 study at Lincoln University. Unlike solar gain, which warms spaces, daylighting means to achieve visual brightness, control glare, and ensure even light distribution throughout interior environments.

Key Factors for Effective Daylighting Design 

• Window positioning: Optimizing the location to capture natural light without causing glare.
• Skylights and solar tubes: Bringing in light from above while minimizing thermal loss.
• Reflective surfaces: Utilizing walls and ceilings that enhance light distribution throughout a space.

A well-planned daylighting strategy not only curbs energy use and costs but also fosters a more pleasant, stylish, and naturally lit environment, as illustrated in Figure 7. In fact, a good daylighting design can reduce energy consumption for electric lighting by up to 75%. Further, by decreasing the need for artificial lighting, which generates heat inside the house, it can cut energy use for cooling the house by 10–20%.

Even better? A review by UCLA Health (2022) found that more exposure to natural light can improve mood, sleep, focus, and overall health.

Figure 7: Abundant Daylight Through Well-Placed Windows in Everyday Spaces

Image by Nur Pexels.com.

Image by Huy Phan via Pexels.com.

These design principles are visible in smaller applications as well, such as the stairway shown in Figure 8. In this 110-year-old house, even an overhead light fixture couldn’t fully illuminate the interior. Now, thanks to a solar tube that channels sunlight from the roof, the stairway is safer and brighter. It is a small intervention with lasting benefits.

Figure 8: Solar Tube Installation – Channeling Sunlight From the Roof Directly to an Interior Stairwell

Image by Courtesy of Annette Olson, CC-BY 4.0

Final Notes on Design

Incorporating the above and other passive design strategies is not just for architects; it is an opportunity for anyone to explore. Whether you are just starting to design your home, updating a single room, undertaking a remodel, or advocating for smarter building choices in your community, using natural elements like sunlight and airflow can reduce emissions, save energy, and enhance your living space’s comfort.  And the benefits extend beyond private homes. Schools, offices, and public buildings can also adopt daylighting strategies to create healthier, more productive, and sustainable environments. By embracing natural daylighting, we take a meaningful step toward resilient communities and a more sustainable future—together.

Additional Resources and Readings

• Passive House Institute
• The Passive House Network
• Orientation | YourHome
• Natural Ventilation | Department of Energy
• Landscaping for Shade | Department of Energy
• Actions for the Built Environment – Architecture 2030
• How to Implement Passive Solar Design in Your Architecture Projects | ArchDaily
• Detail Green Books: Passive House Design | ArchDaily
• The Promise of Passive House Design
• Effectiveness Of Passive Design Strategies In Responding To Future Climate Change For Residential Buildings In Hot And Humid Hong Kong – Sciencedirect
• The Effect Of A Warming Climate On The Relevance Of Passive Design Measures For Heating And Cooling Of European Single-Family Detached Buildings – ScienceDirect

Header image by Jwvaneck via Unsplash.com.

🔜 Up Next in the Series

Curious about what buildings are made of—and why it matters? Don’t miss Part 2: Building Construction Materials, where we explore the hidden climate cost of materials like concrete, steel, plastic, bricks, and glass—and highlight innovative, low-carbon alternatives like compressed stabilized earth blocks, mycelium-based insulation, green roofs, and reflective services. (Coming soon to the Climate Steps site!)

— — — — — — — — — —

Nilgun Duman is a recent graduate with a Master’s degree in International Relations. She currently interns with Climate Steps, where she focuses on building decarbonization, sustainable design, and low-carbon materials. She believes that no action is too small when it comes to protecting the planet.