LEED vs Passive House

As a LEED Accredited Professional, I stand by the benefits of the U.S. Green Building Council's  LEED  rating system and certification, even when people question its alleged greenness and whether it lives up to its hype.

“You get points for including bike parking spaces?” they protest. “C’mon!”

Nonetheless, LEED is a thoroughly useful tool in green design and construction.  I also firmly believe that the additional steps of getting a project certified are worthy and a good investment.  Of course it's not realistic for every project, in which case we work with clients and builders to incorporate green principles on a case by case basis.

Recent conversations, however, have led me to explore other types of sustainable building standards and methods. The Passive House standard, originally developed in the US in the 70's and then perfected in Germany, is also an exciting option for builders, homeowners and developers.  With the founding of the Passive House Institute US, local projects can be certified using criteria that are specific to the US market.

Passive House’s basic premise is to lower energy loads by using building mass with the goal of eliminating building systems.

Check out some photos of Passive House projects on Inhabitat (US and international projects).

“Passive” does not refer exclusively to passive solar heating, often a component of Passive House. The standard goes beyond and requires very high levels of insulation with minimum thermal bridges and thorough consideration of the utilization of solar and internal gains. Passive House seeks to achieve high levels of air tightness, which differs from other building techniques. Contrary to what some may think about air tightness, all Passive House buildings boast first-class indoor air quality because most of them use heat recovery ventilation systems.  You would think it applies only to single family residences by the word "haus", but in fact it can be used for all types of buildings.

But why are there so few Passive Houses?

LEED seems sexier. It focuses on broad categories that can showcase features to the general public. Thre are five areas assessed in LEED: water efficiency, sustainable sites, materials and resources, indoor environmental quality, and energy and atmosphere.

Passive House is easier to explain, but its features are not easily displayed. Its primary focus is energy efficiency, which isn’t particularly attractive when all that can be shared with someone is what type of foam insulation is being used, and that ends up being hidden behind walls. However, actual energy savings can be demonstrated in a concrete way, through minimal energy bills year round.

Also, photovoltaic sunshades or roof-mounted wind turbines are definitely showier versus Passive House’s goal to achieve energy efficiency so great that solar arrays, wind turbines or other complex systems are not necessary or cost effective.

Perhaps another reason that Passive House has not caught on is because the standard is location and climate-specific. LEED does not change based on geographic location. Although the U.S. Green Building Council says LEED is moving toward climate-specific certification, its current point system awards the same points for projects in any region, even though features’ impacts may be completely different.

The client's preferences also heavily influence LEED points pursued. With Passive House, however, either the standard is achieved or it isn’t.

So, which is better?

There is a strong argument that Passive House is the better standard for sustainable development. This is because a building’s biggest impact is its energy usage, and building costs are about the same when compared to LEED buildings (although like all building costs, this depends on the builder and owner).

LEED buildings are found to use 25-30 percent less energy than non-LEED buildings. Passive House buildings can slash the heating energy consumption of buildings by up to 90 percent, and overall energy consumption by 60 to 70 percent.

LEED does not require any minimum air changes per hour, even though building leakage contributes greatly to energy loss. Passive House requires less than or equal to 0.6 ACH at 50 Pascal pressure, which is 10 times tighter than Energy Star.

All in all, the Passive House standard greatly reduces a building’s impact on the environment.

LEED and Passive House do not preclude each other – a building can obtain LEED certification and also meet the Passive House standard.  LEED has been around longer, which might account for greater acceptance, but Passive House might not be far behind.

Local Passive House projects

In this article, "Zero-Energy Construction Crosses the Ocean", some local projects are discussed, including a a multifamily development in Brooklyn at 96 St. Marks Avenue.

A house in Westport has also achieved "Enerphit" certification, which is the Passive House Institute's solution to retrofitting existing buildings and homes.

As energy costs fluctuate (especially heating oil costs here in CT), I think we'll see more interest in Passive House design.  You can find a local Passive House consultant in your area here.