Choosing which sustainable certification to pursue for your building can be difficult.

Most people in the construction industry are familiar with LEED, but there has been a lot of discussion recently regarding Passive House as well. How does LEED compare to Passive House? This article looks at these two certification pathways to help you decide which is best for your building.

Green Building Certifications

First, let’s understand what green building certifications are. These accreditations are created by private organizations or non-profits to provide tools and guidance to design and construct buildings that are more sustainable. They can be used as an independent measuring stick for evaluating your building and communicating how environmentally responsible and/or health conscientious the building is. Over time these certification systems build up an industry knowledge base and start to influence the construction status quo, resulting in buildings and construction practices that are better for the occupants and the Earth. They also enable more accessible communication of otherwise complex metrics to occupants or potential occupants.

Prescriptive or Performance-Based Criteria

As building codes, technology, and sustainability/wellness standards increase, our ways of measuring and gauging them are also adapting. Green building certifications are generally structured using either prescriptive or performance-based criteria. The prescriptive approach provides a checklist of opportunities for individual sustainable components within the building; check enough boxes/gather enough points and certification is obtained. Performance-based approaches focus on the required minimum performance of the building, allowing the designers to find creative solutions to the meet these requirements and allowing an overall holistic design approach. Each approach has its benefits.

LEED (Leadership in Energy and Environmental Design) is a prescriptive green-building certification that was first established in 1993, and quickly became one of the most widespread and recognizable rating systems.

LEED is a step-by-step guide to help architects, designers, owners, and consultants create buildings that are healthier and better for the environment through a variety of methods - including bike parking requirements, decreasing the use of harmful VOCs (Volatile Organic Compounds) in building materials, or sourcing local materials to decrease the greenhouse gas emissions associated with transportation to the site. Over the years, LEED has evolved to have separate categories for different types of buildings. It also has four levels of achievement: Certified, Silver, Gold and Platinum, which are achieved by gaining more prescriptive points. LEED’s focus on gathering points has been criticized for not providing multiple methods to solve a problem and not addressing sustainability in a holistic manner. LEED is now in its 4th iteration and has started to incorporate some performance-based criteria into its point system in an effort to address buildings more holistically.

Passive House is a performance-based green building certification that focuses on limiting total energy use and increasing the interior air quality of buildings.

With strict performance criteria, Passive House is essentially pass or fail - you either achieve the standard or you do not. It was established originally in Germany (called Passivhaus) in 1988 but is now used around the world. As a performance spec, Passive House does not provide possible solutions, but rather relies on the designer and sustainability team to determine the best paths to the goal. These may include thoughtful building façade assemblies that feature robust insulation, thermal bridge mitigation, and high levels of air tightness. This high-performance enclosure’s goal is to decrease - or in some cases completely eliminate - the dependency on mechanical heating and cooling systems. With an airtight façade it is important to provide natural ventilation to every space, typically using a highly-efficient Energy Recovery Ventilator. As a result, these buildings boast superior indoor air quality while dramatically decreasing greenhouse gas emissions and energy use.

So which one is right for your building?

Prescriptive and performance certifications can both positively impact your project. Here are some considerations to help you decide based on your project’s goals:

1. Saving Energy and Reducing your Carbon Footprint. The Passive House standard is established as one of the most rigorous energy reduction strategies. If your primary concern is about reducing your energy use, getting to Net-Zero Ready, or aspiring to Net-Zero Energy, then Passive House is your choice.

2. Marketing. LEED has much broader marketing reach and recognition compared to Passive House. It has become a standard that is recognized even among laymen. If your primary concern is about low risk and broad appeal marketing, then chose LEED. There is a strong positive marketing narrative with Passive House too, but it doesn’t yet have the full name recognition as LEED.

3. Health and Wellness, Indoor Air Quality. Both LEED and Passive House have criteria that involve user health and comfort. LEED covers materials and fixture selection while Passive House focuses on providing filtered fresh ventilation to every space. Also, meeting the Passive House thermal comfort criteria are fundamental aspects of certification. Passive House projects provide superb acoustic insulation between units and the interior/exterior with the airtight and well-insulated façade, ideal for urban or other ‘loud’ sites. We feel that Passive House has the edge in this category even though both can help your project achieve its health, wellness, and indoor air quality goals.

4. Construction and Feasibility. Most contractors are now familiar with the LEED process and effect on the construction process. Passive House is still new in the North American market so there may be some hesitation from the construction side. Owners and contractors are still navigating the feasibility of Passive House for their projects. We believe that whichever path you choose, the contractor should be brought on early in the process. In general, Passive House requires more quality control during construction and it does increase upfront costs 2%-5% more than a code-standard building. If your primary concern is about construction costs and feasibility, we would recommend pursuing LEED. But Passive House is catching up; at the moment the cost difference for Passive House is in switching from double-pane to triple-pane windows, and increases in mechanical systems costs (high-efficiency ERVs and increased duct work). As codes become increasingly more strict and compliance penalties harsher, adopting the Passive House standard will ease energy code compliance, allow you to more resiliently mitigate future agency requirements, while significantly decreasing the energy use and long-term operating costs for your building.

5. Operations, Long Term. Passive House significantly decreases the size of the mechanical loads and will reduce your energy bill. These reductions in operating costs offset the initial increased construction cost. If you are going to be owning and operating your building, then Passive House makes sense as part of an energy reduction strategy.

6. Certification. Both LEED and Passive House have additional costs for consulting services and documentation during the design and construction phases. LEED requires some fieldwork verification and compartmentalization testing during construction. Passive House requires intermittent testing/verification during construction, and full commissioning and air tightness test at the end of construction. Passive House’s additional testing does add up, but also allows you to have confidence that the building will perform as intended by identifying and fixing unsatisfactory details early in the construction process. After achieving either certification you will get a beautiful plaque for your building. Full certification costs less for LEED (depends on your project, but approximately 30% less), but the Passive House certification requires a rigorous 3^rd party test, which ultimately provides value.

7. Design Aesthetic and Budget. We’ve designed LEED and Passive House projects with both large and small budgets. They've incorporated a variety of facade options, including curtainwall, metal panel, brick, EIFS, thermally broken triple-paned storefronts, and uPVC punched windows. All of these projects satisfy their owner's program and budget while also meeting the sustainability criteria. They are also human-scaled and richly-detailed. Both certification paths allow for the full range of your design aesthetic and budget.

8. Embodied Carbon. Both LEED and Passive House have introduced embodied carbon, greenhouse gas, and global warming potential (GWP) tracking to their programs. This tracking is nascent and not fully developed in either program. Passive House’s focus on limiting the amount of energy to operate the building will decrease the total carbon footprint of your project (and coupled with electrification and a clean energy grid will allow you to get to NZR or NZE), but this is purely on the operations side. At the moment enacting meaningful embodied carbon change during construction is not fully integrated by either LEED or Passive House but it is promising that this area is being addressed.

In our sustainable-focused projects we tend to employ both prescriptive and performance design methodologies.

We often use a prescriptive system (like LEED or Enterprise Green Communities) to address material use, plumbing fixtures / water-use, construction waste management, minimum lighting level requirements, community connections, etc. Meanwhile we’ll use performance-based systems like PH to manage energy use, interior air quality, acoustic comfort and thermal comfort. There are also some green-building certifications that use a blend of performance and prescriptive criteria like WELL and Living Building Challenge. The full answer is that selecting a certification program depends largely on your project’s program, location, goals, and constituents.

The House at Cornell Tech, which completed in fall 2017, provides a case study. Here we paired Passive House with LEED allowing the certifications programs to overlap and cover more ‘blind spots’. For example, Passive House does not consider where materials are sourced or if they off-gas and are carcinogenic. But LEED does not model, verify, or monitor how the building actually performs after it is built. Pairing LEED and Passive House allowed The House at Cornell Tech to address sustainable materials, water use, and community access as well as energy efficiency, interior air quality, and interior thermal comfort. By designing The House at Cornell Tech to Passive House standards we were also able to achieve LEED Platinum, ultimately winning the LEED for Homes 2017 Project of the Year.

As energy codes become more stringent and the building industry’s focus shifts toward the impact buildings have on our health and the health of the planet, performance-based certifications like Passive House are an important tool for owners and architects to make positive, real, and measurable change. A blended approach, using prescriptive and performance measures, can be advantageous, but we are increasingly seeing Passive House performance-based design standards as one of the best suited tools for addressing energy efficiency, indoor air quality, and thermal comfort.