building better

I’d give my renovated 1970s apartment building a B minus; it has large reasonably new windows, a moderately insulated facade and radiator-delivered oil heating.  The building I work in is similar, except that it is older and less insulated, so it is chilly in the winter and hot on sunny summer days. Both buildings are typical for Switzerland’s aging urban fabric and would benefit from an upgrade.

As our industrialized societies became wealthier, the amount of energy used to make buildings comfortable increased apace. In the 40 years from 1950 to 1990, US energy consumption rose twelvefold, even the oil crisis in 1974 is only a blip on a graph.[1] Buildings have long been directly responsible for a large part of the global use of resources (fossil fuels, water, land and raw materials) as well as for a large part of generated pollution, waste and excess heat. According to the Global Alliance for Buildings and Construction (GABC)[2], well over a third of global energy is consumed by the construction and operation of our built environment. Under current conditions, this could well rise 50% by 2050. The need to reverse this trend, both for environmental stewardship and geopolitical stability, has been apparent for a long time and over the past two decades many solutions have been tested.

The good news is that many of these measures have proved effective in reducing energy-use. Based on “green-building” principles (e.g. sufficiency, stewardship, sustainability), many strategies also endeavor to improve indoor and outdoor air and noise quality, and increase social benefits for all stakeholders (building owners, end-users, investors and local communities). The GABC, which supports the exchange of information on buildings standards among UN member countries, fosters climate-friendly changes in the construction industry.[3] Among the measures they deem successful are national building codes and standards that set energy-use limits for construction, especially as a prerequisite for building permits.

      Since the late 1990s, various building assessment programs, which are often voluntary and market based, have been developed that have effectively raised construction industry standards and the visibility of sustainable practices. Among the most visible are the so-called “third party certification” programs that analyze buildings before and during construction to ensure that key targets are met. Although many countries and regions have developed building labels,[4] the US-based LEED label is the most well known, with over 65,000 certified buildings in the US, and a further 20,000 worldwide. Vanessa Quirk, writing for ArchDaily, noted that LEED had “taken the “mysticism” out of Green Design”[5] by making energy efficient construction accessible to contractors and building owners alike. The industry as a whole has benefitted from certification. Labels often convey reassurance and carry resale and investment advantages; improved energy performance and cost savings also lead businesses, developers and homeowners to seek certification.

      Although the Swiss building label MINERGIE does not have nearly the global presence that LEED has, with over 45,000 buildings certified in Switzerland, the label has become a domestic bellwether. As a MINERGIE certifier for over seven years, I have observed firsthand how the label has changed not only the way buildings are designed, but also how the construction industry has embraced energy-saving technology and materials. For example, critical joints at roof parapets or balcony slabs are now detailed to eliminate thermal bridges. Changing practices in building orientation and sun-protection have been prompted by certification standards that penalize a reliance on air-conditioning to handle solar gain.

A comparison of LEED and MINERGIE, both celebrating 20 relatively successful years, is insightful as the two programs approach buildings differently. MINERGIE is target-based, requiring building energy-use to fall below a set target. LEED, on the other hand, assesses life-cycle aspects[6] of a building using a point system. Both schemes have been through recent periods of soul-searching, in part because the construction industry has made significant progress towards sustainability, and certification lost its cutting edge advantage. In short, they became victims of their own success. Happily, LEED and MINERGIE have made improvements in 2016 and both labeling schemes could again be seen as the front-runners in their respective areas of influence.

MINERGIE
MINERGIE has its origins in a 1994 research project, supported by the cantons of Bern and Zurich, to build energy-efficient houses.  The MINERGIE label[7] was launched in 1998 with financial support from cantonal and federal governments. Early on, the program certified primarily residential buildings, though local and cantonal requirements increased the numbers of civic buildings. A growing acceptance of the program led to a rise in commercial and institutional certifications as well. To date, approximately 13% of new construction projects in Switzerland have been certified.

      Certification is attained through an evaluation of construction and operational aspects of a building’s design, including information on building components and building systems (heating, ventilation, electrical, etc.). A threshold value (in kWh/m2) for total annual energy-use, using industry benchmarks, is established, which certified buildings must undercut by up to 40%, depending on the label sought. These targets simplify comparison between MINERGIE buildings. Over the past 20 years, stricter thresholds in the form of additional labels (such as MINERGIE-P for passive solar criteria) have led to improvements in MINERGIE’s perceived advantage. Still, by 2016, standard new construction in Switzerland pretty much conformed to MINERGIE requirements. In contrast to the LEED program, there are no requirements for siting or water usage, but an add-on “ECO” sustainability label does consider embedded energy and the sourcing of building components.

      Certification is based on spreadsheet calculations incorporated into an application form, which is available online and free of charge. While it is advised that professional building energy specialists be involved in the process, homeowners have successfully submitted MINERGIE applications for new and renovation projects. Certification costs reflect the amount of time it takes certifiers to assess a project. In many cantons, most renovations and many new buildings obtaining MINERGIE certification qualify for government subsidies.

      As a result of recent changes, MINERGIE requires larger buildings to incorporate a post-occupancy digital monitoring of building systems. All new MINERGIE buildings must comply with a federal recommendation to install photovoltaic panels. A set of five renovation certification “packages” employ sensible but effective measures for older buildings, geared towards improving the overall quality of renovations. A quality control scheme during construction is also newly available.

LEED
The LEED labeling system[8] was developed in the 1990s by the US Green Building Council, with support from the American Institute of Architects and the National Resource Defense Council, with the aim to stimulate best practices for environmentally sustainable buildings. The first LEED building was certified in 1999. From the start, the program has been directed towards commercial and institutional buildings; as a result, the percentage of certified residential buildings is lower than in Switzerland. Due to federal and many state government requirements for LEED certification of new public buildings, many civic buildings are LEED certified.

      Unlike MINERGIE, there are no specific energy-use targets. Rather, LEED employs a system whereby points for various criteria are collected in five assessment areas until a balance towards sustainability has been tipped. The collected points determine the attained standard: silver, gold or platinum. This system allows for a certain amount of flexibility, a building’s lack of, for example, a super-insulated building envelope, can be accommodated for by installing energy-saving appliances, but it makes comparison between buildings difficult. LEED has a stated goal of reducing energy-use by 20 to 30%, which can be hard to ascertain due to the lack of target values. LEED has had to adapt its criteria for some US regions and for international certification. An application can only be submitted by LEED-trained specialists and information about the actual requirements is hard to find online. Costs can be high, even for smaller buildings, which might add to the reluctance of homeowners to consider certification.

      Changes that improve energy-use reductions and user-interface were added in 2016. There has also been an effort to better incorporate further regional standards, especially for worldwide certification markets. The “LEED for Existing Buildings” program provides a simplified path for sustainable renovations. Like MINERGIE, LEED has added a post-certification digital monitoring program.[9]

comparison
Despite their assessment differences, a well built LEED or MINERGIE certified project does ensure green building principles. That MINERGIE has been so successful in the residential sector, while LEED is more visible in the commercial sector leads me to believe that the two programs could learn from each other. MINERGIE’s relative transparent and target-based certification process provides concrete confidence that promises of better energy-usage are kept.  LEED has always given credit for peripheral soft factors such as building location, access to transport and utilities, which are more easily pitched to commercial developers and corporations.

      One of the weaknesses both building labels shared was a sense that design performance did not always match performance in practice. New digital monitoring requirements in both programs aim to ensure that buildings perform to their design standards. These will help uncover ineffective systems and shed light on how building occupants actually operate their buildings.

Thanks to the success of building labels, sustainability in the construction industry has improved substantially over the past two decades.[10]  As noted in the GABC Global Status report, an increased general knowledge of building energy-use leads to building owners and developers making better choices when they build or renovate. The LEED and MINERGIE building certification labels have done much to raise awareness of energy usage in buildings and they have demonstrated a willingness to stay ahead of the market. Learning from each other could help them improve even further.

The next step is to grade ourselves - on how well we use energy efficient buildings.