Designing, constructing and retrofitting buildings guided by LEED, Net Zero or Passive House principles, is not just a marketing stunt. These days mitigating the economic, social and environmental impacts of urbanization is no longer optional.
When it comes to choosing a green building framework, factors to be considered must go beyond their market appeal. The specific features of each building are key to determine the most suitable standard. A building’s use and its users, the local climate and site’s characteristics, as well as budget availability, are all important considerations to take into account. LEED, Net Zero and Passive House, all have their pros and cons:
1. Created in 1993, LEED is the most widely used green building rating system in the world. As a rating system, it accounts points for different building features such as material durability, construction techniques, and efficient use of water and energy. With an uncomplicated framework, this approach is being integrated into building codes and regulations. However, it is this same ease that brings about some of the caveats of the approach. Some of the criticisms include LEED’s weak consideration of the long-term environmental benefits/impacts of a building. For instance, context and energy performance are often neglected. In addition, LEED certification comes with a high price tag that, unrelated to the green features of the building, requires a budget that could otherwise be allocated towards more green features, or even to increase a building’s affordability.
2. The principle behind Net Zero is to produce as much energy as is consumed by a building in a year. Ideally, this energy would be produced on-site and from a renewable energy source, but there is some flexibility. For this reason, the main characteristic of Net Zero is the promotion of buildings that are (almost) off-the-grid, and include solar panels, wind turbines, or geothermal pumps for energy generation. In theory, Net Zero standards can be applied to any kind of building; however, as the square footage of a building increases, its energy demand also rises, making it challenging to generate increasing amounts of energy from a renewable source on-site (you can only fit so many solar panels on a roof, for example). To overcome these obstacles, Net Zero has embraced design strategies that reduce energy consumption: daylighting, high-performance envelopes, and sun control and shading devices, among others. When these strategies are still not enough, other sources of energy (reliant or not on fossil fuels) can be used. Ultimately, the building can just plug back into the grid.
3. Although Passive House has been around since the 90s, Passive House use isn’t as widespread in North America as LEED and Net Zero. The primary characteristic of Passive House buildings is the absence of a furnace or a/c. Passive House buildings are designed to maintain a comfortable interior temperature throughout the seasons. This seemingly simple feature brings down the energy consumption and carbon emissions as low as possible — lower than any other green-building standard can. Moreover, the lack of mechanical systems for temperature and air quality control, also reduces maintenance and operational costs in the long term. But there is more to Passive House than this outstanding feature: with a long-term view, Passive House certified buildings use the highest quality materials and construction systems, and take advantage of the site’s specific conditions, its context and its users. For these reasons, the collaboration between designers, builders, and energy consultants is key to achieve Passive House certification. Furthermore, although going off-the-grid is not a condition for certification, reducing energy consumption to a minimum makes it very easy (and cheap) to reach Net Zero performance. Unlike LEED and Net Zero, not all buildings are suitable for Passive House certification, as energy savings depend a lot on the site’s conditions and orientation, rather than on a building’s size and use.
In summary, LEED and Net Zero certification are widely known and implemented in North America, and although these certifications are easier to achieve, long-term environmental benefits are not necessarily met. Passive House certification can be hard to achieve, but its benefits pursue a stronger effect on reducing GHG emissions, mitigating climate change, and increasing housing affordability in the long term.
In the following blog posts we’ll dive deep into the principles and benefits offered by Passive House.