With each wildfire, lives are uprooted, and homes are lost, leaving communities across the affected regions to rebuild amidst unimaginable destruction. The recent Los Angeles wildfires caused devastating damage, destroying thousands of homes and displacing countless people, leaving entire communities struggling to recover. According to the California Department of Forestry and Fire Protection (CAL FIRE), the Palisades Fire destroyed 6,833 structures and claimed 12 lives, while the Eaton Fire led to the loss of 9,418 structures and 17 lives. Though the cause remains under investigation, the destruction has sparked an urgent conversation about how we can better protect our communities from such devastation.

As the region begins to rebuild, many are turning to innovative solutions for long-term fire protection. One such solution gaining attention is Passive House Design, known for its energy-efficient features and its potential to enhance resilience against future wildfires. But what exactly makes it ‘passive’? And how does it measure up as a viable solution to wildfire risks? With the memory of these fires still fresh, the need for sustainable, protective design has never been more urgent.

The term "passive house design" comes from its emphasis on using passive strategies to maintain indoor comfort, rather than relying on active mechanical systems. In a passive house, the focus is on optimizing natural energy flows such as through high-quality insulation, airtight construction, and the careful placement of windows to minimize the need for heating or cooling. This reduces a building's overall energy consumption and keeps the indoor temperature stable without active systems like furnaces or air conditioners.

To help us gain a deeper understanding of how Passive House design can enhance wildfire resilience, we spoke with Christian Kienapfel, Architect AIA, LEED AP, CPHD, and founder of Paravant Architects.

Based in Culver City, CA, Kienapfel and his team specialize in creating high-performance, energy-efficient buildings that focus on both sustainability and occupant comfort. His approach combines building physics with design, ensuring that each structure performs optimally, improving air quality, acoustics, and overall well-being. With the increasing threat of wildfires and climate change, Kienapfel believes Passive House principles such as airtight construction, advanced insulation, and energy-efficient materials can significantly strengthen resilience against extreme weather events.

In this conversation, Mr.Kienapfel discusses the concept of Passive House, explaining its significance and purpose while elaborating on its core principles.

“What is it? PASSIVE HOUSE (Passivhaus) represents the highest standard in building performance today, offering exceptional comfort, indoor air quality, resilience, acoustics, energy efficiency, and durability.

Why? Typical buildings account for a substantial share of global energy consumption and greenhouse gas emissions, making them a key contributor to climate change.

With the international Passive House standards, you can enjoy enhanced comfort, exceptional indoor air quality, and a healthy, sustainable home with significantly lower utility bills and reduced operational carbon. Beyond minimizing operational carbon, the Passive House Standard also provides tools for analyzing and reducing embodied carbon, offering a holistic approach to achieving a low-carbon future for both residential and commercial buildings.

Image Credit- PARAVANT Architects

Climate-appropriate insulation – A well-insulated building envelope keeps warmer temperatures inside during the cold months and heat out during warmer months.

Airtightness – Passive Houses are designed to avoid leakages in the building envelope, thus boosting energy efficiency while preventing droughts and moisture damage.

Thermal bridge-free design – Avoiding thermal bridges, weak points in the building envelope, contributes to pleasant, even interior temperatures while eliminating moisture damage and improving energy efficiency.

Windows & exterior shading – Strategically positioned, highly insulated, airtight high-performance windows do their part to make optimal use of the sun’s energy or to keep it out.

Continuous ventilation – A Passive House fresh-air ventilation system provides plentiful fresh filtered air free of dust and pollen, maximum energy efficiency through a heat recovery system (HRV), and unlike other ventilation systems, is 100% fresh air (no air recirculation).

Renewable Energy – Once these measures are in place, a much smaller renewable energy and storage system can be added if desired by the owner. On-site and off-site renewable energy production can be seamlessly integrated, enabling the creation of Net Zero Energy (NZE) buildings or even Plus Energy Buildings. The key underlying principle is to first drastically reduce energy consumption through Passive House strategies and then supplement with a much smaller, more efficient renewable system achieving more with less!”

On being asked about the lessons learnt from past Passive House projects, specifically in relation to their performances during adverse events like wildfires, Kienapfel added; 

“We currently have four newly built Passive House projects under construction, along with three Passive House retrofit renovations (EnerPHit) in progress. Additionally, we are working on multiple new Passive House projects in various stages of design, planning, and engineering.

At the end of last year, we completed two small Passive House buildings, which are currently in the process of obtaining certification from the Passive House Institute (PHI). While both buildings are designed as Passive Houses, this project is particularly notable as it is one of the first to be developed under California’s new Senate Bill 9 (SB9), which became law in January 2022. SB9 allows for the creation of up to four living units on a single-family zoned lot, addressing the ongoing housing shortage in Los Angeles by introducing additional residential units on an existing property.

Image Credit- Revepix, Daniel Dilanian; Courtsey - PARAVANT Architects

This SB9 project reflects California’s forward-thinking regulations aimed at addressing the housing crisis while embracing sustainable building practices. Each building is designed as a free-standing structure, and the two buildings are identical mirror images of each other, each with a private outdoor space. The homes are two-story, 2-bedroom, 1.5-bath units, each approximately 900 sq. ft., with large windows that connect the interior to the outdoors, making the spaces feel larger.

During recent fires, we observed that the air filters of the “fresh-air system" were very dirty, indicating successful removal of air pollutants, which was particularly important during the Los Angeles fire events. This demonstrated the effectiveness of the Passive House ventilation system in maintaining healthy indoor air quality, even in the face of challenging environmental conditions.

The occupants have reported multiple times over the past few weeks about the comfort, quietness, and the fresh air experienced while living in a Passive House. They expressed that the difference in comfort was significantly more noticeable than in typical homes, something they didn’t expect. The superior indoor climate, soundproofing, and constant supply of fresh air provided by the Passive House design have greatly contributed to their overall living experience, highlighting the distinct advantages of this construction standard.

My key takeaway as an architect from working on these very small Passive House buildings is that even compact structures can successfully achieve the stringent airtightness requirement of 0.6 ACH@50, as set by the Passive House Institute for certification. Our contractor and his team not only met but exceeded this standard, demonstrating that quality control is one of the most crucial aspects of the process. Additionally, Passive House certification serves as a vital tool in keeping the entire team focused and committed to delivering the best possible results for the client.”

Lastly, we asked Mr. Kienapfel on his thoughts regarding why Passive houses should be considered, especially in light of the challenges that the wildfire risks in the future.

“Upfront, it's important to note that there are no “fireproof buildings" in existence, and Passive House buildings have also suffered fire damage or destruction in some cases. However, Passive House design offers distinct advantages that make it a more resilient solution in wildfire-prone areas.

For example, the simple building geometry commonly used in Passive House construction is much more appropriate from both a thermal and seismic perspective, reducing complex shapes where wind-driven embers might get trapped. The design’s simplicity also limits potential points of entry for embers, improving the building's overall resistance to fire.

The airtight envelope of a Passive House, compared to conventional construction, significantly reduces the likelihood of ember intrusion driven by high winds. This airtightness, combined with high-performance windows and doors typically made to meet rigorous thermal performance standards also means these elements are structurally stronger and more resistant to fire than standard windows or doors found in conventional homes.

The airtightness of a Passive House significantly reduces smoke infiltration during high air pollution from local fires. This helps maintain a healthier indoor environment by preventing harmful particles from entering the home.

However, it's essential to emphasize that Passive House can only be truly effective when combined with fire-resistant and non-combustible materials. This includes fire-resistant cladding and roofing materials. Additionally, creating a sufficient defensible space around the building, using non-combustible landscaping materials, and managing vegetation all play a critical role in fire prevention and protection."

The catastrophic impact of recent wildfires in Los Angeles serves as a stark reminder of the urgent need to rethink how we build our homes and communities in fire-prone areas. While no building can be entirely fireproof, Passive House design offers a powerful strategy to enhance resilience in the face of increasing wildfire threats. By focusing on airtight construction, energy-efficient systems, and materials that can withstand extreme weather, Passive Houses provide an innovative solution to reducing vulnerability, not only to wildfires but also to the broader challenges of climate change. As the rebuilding process begins, integrating sustainable, protective designs like Passive House could play a crucial role in safeguarding communities, offering a more resilient and sustainable future. With lessons learned from past projects and increasing attention to the role of architecture in fire safety, the potential to reshape our homes for better protection is within reach, one design at a time.

The top image in the article © CAL FIRE_Official/Flickr (CC BY-NC 2.0).

> via PARAVANT Architects

building safety passive architecture resilience wildfire