Can Passive House, LEED & Mass Timber work together to multiply benefits of each system?!

In today's blog I'm discussing the potential of going all the way to minimizing carbon footprint of buildings and site while boosting residents health and save energy and heating bills. These three systems are currently at the forefront of fighting global warming and enhance occupants' health. The first system in my list is the Passive House standard.

1. Passive House: superior efficiency, comfort & health

According to the Passive House Institute, Passive House is a building standard that is truly energy efficient,comfortable, affordable, and ecological at the same time. Passive House is not a brand name, but a construction concept that can be applied by anyone and that has stood the test of practice. Yet, a Passive House is more than just a low-energy building.

Characteristics of a Passive House building

·        Passive House buildingsallow for heating and cooling related energy savings of up to 90% compared withtypical building stock and over 75% compared with average new builds. In termsof heating oil, Passive House buildings use less than 1.5 litres per squaremeter of living space per year – far less than typical low-energy buildings.Similar energy savings have been demonstrated in warm climates where buildingsrequire more energy for cooling than for heating.

·        Passive House buildings arealso praised for their high level of comfort. They use energy sources insidethe building such as the body heat from the residents or solar heat enteringthe building – making heating a lot easier.

·        Appropriate windows withgood insulation and a building shell consisting of good insulated exteriorwalls, roof and floor slab keep the heat during winter in the house – and keepit out during summer.

·        A ventilation systemconsistently supplies fresh air making for superior air quality without causingany unpleasant draughts. This is e.g., a guarantee for low Radon levels andimproves the health conditions. A highly efficient heat recovery unit allowsfor the heat contained in the exhaust air to be re-used.

Now that we know what Passive House is about, lets move on to the 2nd system - Leadership in Energy and Environmental Design-LEED.

‍2. LEED: carbon & resiliancy

LEED encourage innovation of the design process but also focuses on several aspects related to the building project including site, water, materials and sustainability of site. According to Canada Green Building Council CACGB, LEED is a certification for building that provides independent, third-party verification that a building, home or community was designed and built using strategies aimed at achieving high performance in key areas of human and environmental health: location and transportation, sustainable sitedevelopment, water savings, energy efficiency, materials selection and indoor environmental quality.

Canada's Position vis a vis LEED

Canada is rated 2nd in LEED certified buildings outside the US. Thomas Mueller, President and Chief ExecutiveOfficer of CaGBC says that “With climate change on everyone’s mind, the newly launched version of LEED makes it easier than ever before to achieve high performanceand scale-up market adoption to reduce carbon emissions and increase the resiliency of buildings.”.

LEED is a holistic design approach that takes care of all the design aspects of the building project, from Site planning to specifications of "green" materials and reward points for each of these categories. In my view one of the major pillars of LEED is improving occupants's health through its focus on materials and their resources that can minimize embodied energy and other impacts associated with the extraction, processing, transport, maintenance, and disposal of building materials. This as can be seen, goes beyond the design efficiency of the building envelope.

3. Mass Timber: sequentered carbon!

According to Natural Resources Canada, "with the wide range of mass timber uses and applications, as well as the increased availability of new building materials on the market, wood is a preferred option for low carbon/green construction" .It goes on to say that growth in mass timber construction across Canada can be linked to progressive building codes, new mass timber products, innovative building systems, a growing number of designers and builders with expertise, increasingly affordable products and systems, and interest in green building materials and sustainable designs.

Mass timber projects are defined as public and private industrial, commercial, institutional and multi-family residential buildings that are at least 300 square metres. These buildings use engineered wood components or assemblies in structural applications, such as walls, floors and roofs either in all-wood designs or as a key part of a hybrid system (with steel, concrete and/or light wood frame). The report and map also features other structures such as bridges, towers and agricultural buildings. The game-changer benefit of MT is that carbon is actually removed from the environment and stored in the wood — the sequestered carbon. With Mass Timber buildings the building becomes a carbon sink rather than a source of carbon emissions into the envirornment.

How Each Compliments the Others?

Because Passive House standard aims at lowering energy demand in buildings to unprecedented 15 KWh/sf. annually, and to create the best air-tight system, it provides the best methodology of achieving energy efficiency and indoor air quality.

To a certain degree Passive House is not concerned with other aspects of sustainability such as water consumption, site features such as heat island effect, proximity of public transportation in the area, or providing bike racks and permeability of surfaces and so on. Passive House main focus is the building envelope and its superior design (no thermal bridging) . Note that the word House in Passive House does not mean strictly a house, but rather a building. (Haus in German means a building too).

LEED considers a wider range of issues in addition to energy efficiency namely environmental impact such as location and transportation, sustainable site development, water savings, energy efficiency, materials selection and indoor environmental quality.

In Chapelview in Burlington ON, the first LEED Platinum Affordable Housing project was built (see image below). According to LEED, one of the easiest and most effective ways to lower water consumption in buildings is to use low-flow fixtures for faucets, toilets, and aerated showerheads; the front-load laundry washers also saveswater. Other recycled materials used in the construction included: Forest Stewardship Council (FSC)-certified wood; wheat-based products for doors; soya and recycled plastic bottles for sprayed polyurethanefoam (SPF) insulation; and 100 per cent recycled drywall.

Finally, mass timber as a construction system and material has tremendous environmental benefits. Basically timber makes the building a carbon sink rather than emitting carbon.

Though mass timber offers many benefits over traditional building materials, its renewable nature and negative carbon impact are perhaps the most exciting. Turning trees into timber emits fewer greenhouse gases than the manufacture of traditional building materials like steel and concrete. That alone is a carbon benefit. However, it’s the carbon that is removed from the atmosphere and stored in the wood — the sequestered carbon.

Tthat is actually the real game-changer. Mass timber has the potential to be more than just a carbon-light construction method. It can become a carbon sink. Industry advocates claim that by 2034, the North American construction industry as a whole will store more carbon than it emits. (for source click here)

In conclusion, I think that implementing the three systems in our current and future projects can yeild great benefits for the environment but mainly on the health and comfort of occupants. The Passive House, LEED, and Mass Timber design / construction systems can all work together to make greater buildings than implementing each system individually. Luckily these three systems do not started out to solve the problem of carbon dioxide emissions but that can only mean healthier and more comfortable homes, offices, outdoor spaces and communities at large.

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