Meeting and Exceeding Energy Standards with BIM Software

Building design professionals rely on building information models and other computer software as integrated tools for design and performance

By Peter J. Arsenault, FAIA, NCARB, LEED AP

Energy efficiency in buildings has been a hot topic ever since the 1970s oil crisis focused public and private attention on the matter. Since then, an increasing number of mandatory and voluntary codes and standards have been developed that impact building design. Each of them have been updated and sometimes expanded based on input from regulators, designers, constructors, owners, and others. All of these codes and standards have been informed, and in part made possible, by the availability of computer software programs that allow for total building assessments of energy use under defined conditions. Beyond creating a separate, computerized energy model of a building, architects and other design professionals are now also able to use building information model (BIM) software to design, assess, and revise a building to achieve targeted levels of energy performance. Some BIM software has inherent energy analysis capabilities, while others link to separate specialized software based on information available in the building model. In this course, we will look at the current status of some of the best-known and most-used energy codes and standards, and how computer analysis is an integral part of not only demonstrating performance, but also a tool that helps with making better design decisions.

Establishing Minimum Standards with Energy Codes

While most architects and engineers are familiar with the need to address energy codes, there are in fact multiple codes that may be in play at any given time.

International Energy Conservation Code

The International Code Council (ICC) was formed in the United States in 1994 as a singular model code agency that consolidated three prior model code organizations (BOCA, ICBO, and SBCCI) that each had limited applications in different parts of the country. The resulting family of International Codes, or I-Codes, includes a full range of integrated building, fire, and other codes that are publicly reviewed, revised, and vetted by regulators and design professionals on a three-year cycle. Jurisdictions in all 50 states, the District of Columbia, and many federal agencies have formally adopted versions of the I-Codes, with or without amendments, as the governing code for their jurisdictions. This currently includes the 2009, 2012, and 2015 versions of the International Energy Conservation Code (IECC), all of which have the same intent: the IECC “regulates the design and construction of buildings for the use and conservation of energy over the life of each building.”

In order to achieve this goal of energy conservation, the IECC addresses four primary areas that are designed and specified directly by architects and engineers:

1. The building envelope (or building enclosure), including insulated walls, floors, and roofs; fenestration such as windows, doors, and skylights; and reducing air infiltration. It is generally regarded that addressing all of these areas first is the most cost-effective and efficient means of reducing a building’s need for energy to run the other three systems below.
2. HVAC systems, including requirements for proper system sizing, equipment efficiencies, controls, and other items.
3. Service hot water systems that heat water for any purpose other than space heating (i.e., bathrooms, kitchens, laundries, etc.)
4. Electrical systems used for lighting and electrical equipment.

As adopted, the IECC applies to virtually all new or renovated residential and commercial buildings that contain conditioned space (i.e., heating, cooling, and/or ventilation) with almost no exceptions. In a very real sense, it is the basic, minimum energy conservation standard for all new and renovated buildings in the United States. The not-for-profit organization Building Codes Assistance Project (BCAP) monitors adoption of the different versions of the IECC across the country and advocates for responsible improvements during the three-year review process. Maureen Guttman, AIA, president of BCAP, points out the significance of architects participating by noting, “It is imperative that architects become engaged in the development of building codes, especially the advancement of the energy code, to ease the burden that code compliance has on a firm. More so than other codes, the energy code allows architects to associate value with their design strategies, and therefore it gives them more influence with clients on design decisions.”

ASHRAE 90.1

During the time that the IECC was being developed in the 1990s, the American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) was also developing a standard for energy-efficient design in commercial buildings. Currently known as ANSI/ASHRAE/IES Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings, it has similarly been updated regularly since 1999 with input primarily from the engineering community. As of 2017, the versions in use around the country include the 2010, 2013, and 2016 editions. The IECC recognizes this standard as producing energy performance equivalent, albeit not identical, to its own buildings. Therefore, the code allows this standard to be selected and followed to demonstrate compliance for commercial buildings, provided it is used singularly for that purpose—it is not possible to select some provisions from the IECC and others from ASHRAE 90.1 within a single building design. The reasoning is simple: they each have slightly different requirements that work together to produce an efficient building system but cannot be mixed and matched and still show the same results. Generally speaking, the IECC has more stringent building envelope requirements, while ASHRAE 90.1 has more stringent mechanical and electrical requirements, although actual differences will vary based on building types, sizes, and other details.

Designing to Comply with Code

Once a decision is made to follow the provisions of either the IECC or ASHRAE 90.1, how do architects tend to incorporate and demonstrate the needed energy code compliance? The answer varies by project and by firm, but there are two fundamental options. The first is a “prescriptive” compliance path, which amounts to essentially following checklists of traits or characteristics of specific building components (i.e., walls, windows, HVAC equipment, etc.) meeting certain minimum performance or efficiency requirements.

Since this is a fairly restrictive process that relies primarily on very conventional construction techniques, many firms tend to prefer the second option, which is based on performance. In this case, a building is considered as a single system rather than a collection of discrete parts. The code doesn’t dictate design, but it requires any building to demonstrate that its overall performance meets or exceeds code minimum overall performance comparable to meeting the prescriptive levels.

Under a simple performance approach, design trade-offs are allowed in the building envelope so that, for example, a building with less insulation in the walls than prescribed in the code can potentially make up for it with better windows or more insulation in the roof, as long as the overall building energy performance is met. For simple trade-offs of this nature, a computerized analysis using free ComCheck or ResCheck software from the U.S. Department of Energy is common and suitable based on either the IECC or ASHRAE 90.1. However, for more involved designs where the construction systems may not be completely conventional, or where glazed areas make up more than 30 to 40 percent of the building wall area, or where trade-offs involving mechanical or electrical systems are needed, then a full, computerized energy model is required to demonstrate code compliance. Under this scenario, the entire building and all of its systems must be modeled by computer, first in a baseline version where all prescriptive conditions are met and then in a version based on the proposed design. When comparing the two, the design must demonstrate that it will cost less in terms of energy than the baseline version, all other things being equal.

Fortunately, most architectural and engineering firms use computer-based design programs for their projects, including a growing number that rely on building information models. With this technology, architects can assign the specific design attributes of all of the building components and assemblies into a virtual, three-dimensional model. Since the model is made up of BIM objects that can be fully defined by architects, they include embedded data that can automatically update itself if dimensions or other aspects of an object are revised during design. This data can also include the full scope of a product’s materiality in terms of form, texture, color, and other attributes. Beyond the individual objects, the entire building can be modeled as a whole within the computer software. This allows for the three-dimensional geometry to be fully documented and for the computer to perform complex spatial calculations in a fraction of the time it would take to do by hand.

The embedded data and associative capabilities can also be used within the BIM program to perform some fundamental energy calculations or to assess things that affect energy, such as daylighting and solar heat gain. Either way, the BIM software and processes are direct ways to help designers provide the needed information to run a full energy model and demonstrate code compliance. It should be noted, however, that the most effective time to perform this analysis is not at the end of the construction document stage, but rather all throughout the design process, starting at the earliest stages. Most BIM and energy modeling software make it easy to try different variations or iterations of a design to see the comparative impacts of a given decision on energy usage in a building. That means a series of quick, schematic level mass and glazing studies can reveal design combinations or schemes that improve or impair energy performance. It also means that the designers can learn early what works best for their specific building project in its particular location and easily make informed design adjustments as required. Waiting until later to learn that a building does not perform as hoped will likely involve a lot more reworking of the design and documentation by the architects and engineers involved—a potentially time-consuming and costly process for the team.

International Green Construction Code

In 2012, the ICC released a new code document that addresses green building design beyond the basic energy-efficiency requirements of the IECC. The International Green Construction Code (IgCC) is the first model code to include sustainability measures for the entire construction project and its site with the expectations of making buildings more efficient, reducing waste, and having a positive impact on health, safety, and community welfare. It addresses conservation of natural resources, materials, energy, and water, as well as indoor air and environmental quality. While it uses the “model code” approach of the ICC, it also provides communities with the ability to modify the code to suit their particular local conditions. As such, it allows variation and electives for minimum and advanced levels of performance through both prescriptive and performance options. While it is a stand-alone document, it is important to note that it does not replace the IECC or other building codes, but rather is designed as an overlay to the ICC family of codes. Most states consider this an optional or voluntary code for jurisdictions to consider, thus far with a comparatively lower rate of adoption than other codes.

Raising the Bar with LEED and ENERGY STAR

While the codes set the basic, required level of performance, many design professionals and building owners have been interested and committed to doing more than the minimum. Over the past 20 years or so, two significant voluntary programs have emerged for buildings that promote energy and building performance that is better than code minimums.

Leadership in Energy and Environmental Design (LEED)

The U.S. Green Building Council (USGBC) was established in April 1993 when representatives from 60 design firms and several nonprofits gathered in the board room of The American Institute of Architects (AIA) in Washington, D.C., for the council’s founding meeting. Their stated mission was to promote sustainability-focused practices in the building and construction industry. That has been achieved through a membership that reflects an open and balanced coalition spanning the entire building industry. The flagship program of the USGBC is the green building rating system known as LEED, which was first unveiled in 2000 and has since become an international standard for environmentally sound buildings. The premise behind it is that an objective third party reviews information submitted by design and construction teams to ascertain a building’s level of sustainability and then issues a certification accordingly. Currently, hundreds of thousands of square feet are certified under the program around the world each day.

In addition to energy use, the LEED program addresses a full range of sustainability categories in buildings, including the site, water use, materials and resources, indoor environmental quality, and others. Different versions have been developed in an open, reviewed process with custom variations for different building types, such as schools, hospitals, homes, data centers, etc. In all cases, obtaining certification requires meeting some basic prerequisite requirements under the different categories and then demonstrating how the building achieves points in the scoring system (essentially on a scale of one to 100) under different credits available in each category. Depending on the number of total points achieved, a building can be recognized at the Certified (basic), Silver, Gold, or Platinum levels.

The latest release of the system is LEED version 4 (LEEDv4), which requires higher levels of energy conservation than prior versions. Under the Energy and Atmosphere credit category, the prerequisite for a building to be considered is a demonstrated improvement of 2 to 5 percent (depending on building type) in energy conservation compared to a baseline building using ASHRAE Standard 90.1 (2010 edition). This means that the building has to be slightly better than code just to be eligible for the program. After that, the design can earn between one to 20 points (the largest single potential area for earning points in LEED) based on demonstrating additional energy use reduction from between 6 to 50 percent of the baseline; the more reduction, the more points. In order to qualify, a full energy model is required following the guidelines of the LEED program and ASHRAE 90.1—some of which can be a little different than the IECC guidelines. Once again, this is where having the basic data in a computerized BIM model can save time and money while fostering creativity in design. The core information and design criteria can be the focus of design and exported as needed to other programs to demonstrate the needed performance.

In addition to the pure energy usage, the Environmental Quality category addresses things that are important in their own right but can also influence energy use. As such, they need to be addressed in the building design from multiple vantage points with multiple variables, which makes them particularly appropriate for computerized analysis. Daylighting and Views in this category addresses how the building design provides occupants with views to outside and allows natural daylight inside. These traits are good for people but may also mean that electric lights can be dimmed or turned off when conditions are right, thus requiring less electricity use in the building. Conversely, too much sunlight might cause the building to heat up more than desired and require more energy to run air-conditioning systems. The key is in finding a balanced design, which is where multiple computer simulations can be invaluable.

Increased ventilation is another condition of good indoor environmental quality since having plenty of fresh air in places where people are located is both desirable and healthy. Of course, that means the fresh air needs to be conditioned for temperature and humidity like the rest of the air inside the building, which requires energy. Some of the techniques in this situation include better controls to require ventilation only when people are present in rooms or heat exchange systems that condition incoming ventilation air by reusing the temperature of the outgoing air. Indeed, some basic levels of these things are mandatory provisions of the IECC, but LEED allows and encourages more creative and inclusive approaches. These might include the use of “solar chimneys” that induce natural ventilation air flows instead of requiring electric fans. It might also involve night cooling techniques where a building is flushed with fresh air overnight to cool it down so less air-conditioning is needed in the morning. Any of these techniques need to be simulated on a computer and shown how they are effective for providing the needed levels of ventilation while reducing the need for electrical energy. BIM models and associated software can be critical in producing the needed simulation and documentation for these areas.

ENERGY STAR for Buildings

Most people recognize the familiar blue and white ENERGY STAR symbol found on everything from appliances to computers, but many design professionals and building owners are also taking advantage of this program for buildings. ENERGY STAR for buildings is a national program administered by the U.S. Environmental Protection Agency (EPA) that looks at all aspects of energy use and conservation in buildings. In order to earn this certification, a building must show a predicted (i.e., energy model) or actual (i.e., utility bills) energy performance that produces a score of 75 or better, which represents at least 20 percent better energy performance than an established baseline for similar buildings. The program is specific to different building types and geographic regions, and it uses the Commercial Building Energy Consumption Survey (CBECS) as the data source for its baseline.

Some of the aspects of this program have become fairly mainstream tools for the energy-conscious design and construction of buildings. First, it identifies a distinction between the amount of energy consumed on-site in a building (e.g., utility meter readings) and the amount of raw energy that was required at the source to produce the delivered energy (e.g., fuel at a power plant). When normalized to be measured in basic, common units of energy such as British thermal units (BTUs), it is typical to find that the energy used in a building actually requires two to three times that amount at the source due to generation and transmission losses. Hence, the ENERGY STAR program brings attention to the multiplier effect of energy use reduction in buildings by identifying both source and site energy. It also provides direct mathematical calculations for the amount of carbon dioxide (measured in tons) that is produced at the source based on the amount of site energy used.

While this may all sound good at a high level, the question naturally becomes how to compare buildings fairly. Like all common building comparisons, breaking things down on a square-foot basis according to building type seems to be the most equitable, just as is commonly done for cost estimating. In the case of energy use, all building energy sources (electric, natural gas, etc.) are converted to BTUs for a uniform comparison. Then, the total number of BTUs required for the building over the course of a year are calculated and divided by the square footage of the building. This provides an annualized unit of comparison that is referred to as energy use intensity (EUI) and is expressed in terms of thousands of BTUs (kBTU) per square foot per year. So, for example, a building with an EUI of 75 is portrayed as requiring 75,000 BTUs for every square foot per year. If a similar type of building is constructed nearby and has an EUI of 37.5, then it has an energy use intensity that is half of the first one.

ENERGY STAR offers some free online calculators known as Target Finder and Portfolio Manager that allow design firms to quickly and easily identify data for their buildings. These include the building EUI, the ENERGY STAR score, the amount of site and source energy consumed, and the carbon dioxide savings potential. However, to run these numbers with any accuracy, the total building energy usage needs to be known. For existing buildings with a year’s worth of actual energy bills, that is a matter of tallying and entering the data. For buildings in design, it requires running a computer energy model based on the proposed design of the building. BIM data can once again inform the energy model, which can produce an overall energy usage profile for the year. That data can then be used as input for the ENERGY STAR calculations.

Net-Zero Energy Buildings and the Architecture 2030 Challenge

The modern concept of net-zero energy buildings (NZEB) has been around for at least the past few decades but has been defined in different ways. Some people mistakenly think it is a building that uses zero energy. While that may have been possible for cave dwellers and nomadic tribes, it is not what is intended here. Rather, it is the concept of reducing the demand for energy in a building to the point that on-site renewable energy sources (such as solar and wind power) can supply as much or more energy as the building consumes. ASHRAE has defined this concept further by stating that a true NZEB produces as much renewable energy as the source energy that it consumes. Fundamentally, everyone recognizes that modern buildings will require some energy to power devices and conveniences, but the way that power is produced can be more sustainable than relying on fossil fuels. It is also understood that most buildings will still be connected to a power grid or other utility infrastructure both to cover the times of the day or year when renewables aren’t available (i.e., no solar at night) or to sell excess energy back to the utility. Hence, for our purposes, we will define a net-zero energy building as one that produces the same or more on-site renewable energy in a given year than it consumes from outside fossil fuel sources. With this in mind, there are two national programs worth discussing.

The 2030 Challenge

Architecture 2030 is a non-profit organization founded by architect Edward Mazria, FAIA, in 2002. He has successfully publicized reliable data demonstrating that buildings account for nearly half of the overall energy usage in the United States and more than 70 percent of the electricity consumption. Hence, any strategy to save energy or reduce pollution emissions from fossil fuel usage will necessarily be directly impacted by working toward net-zero energy buildings. The specific strategy proffered by Architecture 2030 is contained in the 2030 Challenge. Simply stated, the 2030 Challenge is a series of design targets for buildings to gradually reduce their fossil fuel energy consumption. The current target is to design and renovate buildings to use 70 percent less fossil fuels than the regional average. The targets grow every five years to 80 percent less by the year 2020, 90 percent less by the year 2025, and 100 percent less (i.e., zero fossil fuel usage) by the year 2030. This goal is for all new buildings, as well as an equal amount of existing buildings, and for all types—residential, commercial, institutional, and industrial.

How do we get there? By using the same principles we have been discussing: better building envelope design, holistic energy conservation, improved building system performance, plus on-site renewable energy generation. To get to net zero, however, we need to pay attention to all of the details of these things, going well beyond minimum code levels and even beyond LEED and ENERGY STAR levels. The phased approach over time is meant to allow the design and construction community the chance to ramp up practices and procedures and incorporate them into building projects. Some have suggested that this can be accelerated by having building owners simply purchase all of their energy from renewable suppliers over the utility grid. Architecture 2030 has responded with a very realistic approach that reflects the ability of the utilities to meet such a demand by indicating that no more than 20 percent of the energy needs of a building should be expected from off-site (utility company) renewable sources for electricity. The other 80 percent needs to be accounted for in design, system efficiencies, and on-site renewable energy. Architects and engineers who have pursued this goal have been successful by using computer analyses to account for the same design variables we have been discussing, as well as the specific parameters of the 2030 Challenge.

AIA 2030 Commitment

In 2006, the national AIA Board of Directors adopted the 2030 Challenge on behalf of the entire architectural profession. In order to document the progress of firms in meeting the targeted goals, the AIA 2030 Commitment was developed as a voluntary reporting program for firms to use. To participate, firms sign a commitment letter, identify their own sustainability plan, and report annually with some very fundamental data on each project in the office. Since the year 2010, design firms from all over the United States have been tracking and reporting on all of their projects, not just award winners, with more than 2.6 billion square feet of project work reported in 2015 alone.

The type of reporting information asked for is fairly straightforward. After some basic descriptive information (project name, building type, square footage, stage of design), a baseline EUI and the predicted EUI (pEUI) based on the design is requested. The baseline is most readily determined from the ENERGY STAR online Target Finder database. The pEUI is ideally calculated from a computerized energy model or, at the very least, a calculation based on current minimum code compliance. The difference between the baseline EUI and the pEUI, expressed as a percentage, is then readily determined for each project and ultimately as an average for all of the firm’s projects. If the total currently comes out to a 70 percent reduction or better, then the firm is on track with the 2030 challenge goals. If not, it lets designers know so they can respond in their design process accordingly. For projects that are limited to interior upgrades, a full EUI comparison is not needed, but a similar calculation for lighting power density (LPD) is needed. This is a fairly straightforward calculation of dividing the number of watts of electricity needed for interior lighting by the total number of square feet that are lit to determine the watts per square foot. The actual LPD of the design is then compared to the baseline thresholds in the IECC or ASHRAE 90.1 to determine if there is improvement to the lighting efficiency.

One of the earliest firms to sign on to the AIA 2030 Commitment was Kipnis Architecture + Planning (KAP) in Evanston, Illinois, headed by Nathan Kipnis, FAIA. He notes that the firm is “guided by the idea that architectural design excellence need not be sacrificed for principles of sustainability. Rather, we believe green design expands the possibilities for innovative architectural forms, construction methods, and the use of materials.” With a particular dedication to significantly reduce the carbon dioxide emissions from as many of its building projects as possible, the firm takes the approach of reviewing and assessing its work throughout the design process in a holistic or “total systems integration” manner. A large part of its success in this regard has been based on its use of BIM and related computer software on projects of all sizes and types. Typically, the firm starts with a baseline design and then compares individual components or systems using whole-building computer modeling. As the best-performing solutions are determined, the designers can make incremental design decisions based on the impact of each component as demonstrated in the modeled performance. The firm points out that the real opportunities to find improvements to energy performance are at the beginning of the design process, not later—by understanding the impacts early, adjustments can be made easily and efficiently to optimize the design. As a small firm, it has found essentially no barriers to employing this process since there are plenty of easy-to-use, affordable computer programs available.

Nathan has seen the 2030 Commitment program grow and evolve in recent years and notes that “the main difference of late has been the AIA’s much more formalized Design Data Exchange (DDx) platform for recording predicted project energy use. The DDx is very interactive and provides for comparisons between a specified group of projects.” He also likes the fact that a firm can store up all of the information on its projects in one place online and refer to it as needed. By utilizing the DDx, a firm can not only see how it is doing internally, but it can also anonymously compare its projects to the work of other firms. This helps the firm gauge its relative performance among its peers, which some firms have used in their marketing strategies to gain new clients or better serve existing ones.

Taking It to the Max: Passive House and the Living Building Challenge

By now it should be clear that many design professionals and others are engaged in creating buildings that are increasingly energy efficient and sustainable. In some cases, there are those who have realized that there is no reason to wait until the year 2030 or even 2020 to create net-zero buildings—it is technologically possible and economically achievable now. Two programs are leading the charge in this regard.

Passive House

In the 1980s and 1990s, researchers in Germany began looking at ways to achieve extreme reductions in energy use in residential buildings. That work led to the creation of the German “Passivhaus” and the international Passive House Institute (PHI), which develop standards for buildings with a 90 percent reduction in energy consumption compared to typical buildings. In response to the growing number of people internationally who began to embrace the principles behind this work, the membership-based International Passive House Association (iPHA) was created. In 2007, the work of this group influenced a small group in the United States to create the similar, but separate, Passive House Institute US (PHIUS) and the membership-based Passive House Alliance US (PHAUS). In 2015, these not-for-profit U.S. groups, with public and private funding, developed updated standards that were adjusted to suit the different climate conditions across the United States. Known as the PHIUS+ 2015 standard, it targets performance levels that balance investment and payback, thus presenting an affordable solution to achieve comfort and cost-effective energy efficiency using the best path to net-zero energy. The cost-optimized PHIUS+2015 standard has spurred new growth in passive buildings across the country, with the most significant gains coming from the multifamily housing sector. Overall, Passive House has rapidly grown in popularity, with more than 60,000 housing units in place worldwide as of early 2017, including more than 1.1 million square feet across 1,200 units in the United States.

The principles behind Passive House design and construction focus first on optimizing the building envelope, specifically by relying on super-insulation levels, complete air infiltration control, and high-performance products, such as doors, windows, sealants, etc. The concept also recognizes the capability of the sun to provide a noticeable amount of passive solar heat gain in cold months, while using natural or added shading in the summer to help keep the building cool and comfortable. Because of these critical first steps, a full HVAC system is often not required. Instead, only a small air ventilation system with supplemental heat and humidity control is typically enough to keep everyone comfortable. Further, since the energy demand is so low, adding a small solar electric/photovoltaic (PV) array becomes a very affordable way to get to net-zero energy.

In order for a building to be certified under the Passive House program, the designer must complete training to be certified under a PHIUS program. One such designer, Markus Barrera-Kolb, a project architect and Certified Passive House Consultant (CPHC) with Whitney Architecture in Seattle, provides a good perspective on engaging in the program. First, he points out that verification of designs relies on using a computer analysis based on specific PHIUS software developed in cooperation with the Fraunhofer Institute for Building Physics, which is known as WUFI Passive and available in both a free and paid version. “While some BIM software isn’t yet ready for direct use in Passive House modeling, in our office, we’ve worked over the past few years to maximize the benefit of our BIMs in obtaining the data for our Passive House energy models as efficiently and accurately as possible,” he says. Some other architects also report using their 3-D BIMs in conjunction with the Passive House software as being highly beneficial because they find it to help both efficiency and quality control.

Markus Barrera-Kolb also comments on the impact of being trained in the principles of Passive House design, saying, “I can’t overstate the significance and usefulness of Passive House. Even for architects who may not end up modeling their own projects, or for that matter even work on certified buildings, the in-depth knowledge and applicable skills and tools that are gained through Passive House training will make a huge, positive impact on their practice going forward.” Clearly, he sees the value in bringing the design principles of Passive House to all projects that a firm works on and echoes what others have found as well. Namely, that Passive House design empowers them as designers while helping to communicate to clients how using key building science principles and technologies directly translates to added value for them.

Living Building Challenge

The Living Building Challenge is a program that was initially launched by the Cascadia Green Building Council in the Pacific Northwest. The not-for-profit International Living Building Institute was created in 2009 and renamed in 2011 to the International Living Future Institute (ILFI), becoming the umbrella organization for both the Living Building Challenge and the Cascadia Green Building Council. Now in its third version (LBC v3.1), The Living Building Challenge is considered the world’s most rigorous proven performance standard for buildings based on a philosophy of going further than just minimizing the harm a building inflicts on the environment to creating structures with positive impacts and, in turn, promoting a living future.

In order to achieve certification, Living Buildings must demonstrate that they have actually achieved this positive effect. It is good to be net zero for energy, but they seek to achieve net-positive energy—generating more renewable energy than the building needs so others in the area can benefit too. The same is true with net-positive water—collecting and treating more potable and non-potable water on-site than they use and treating the waste on-site to avoid stress on local infrastructure. Similarly, they achieve net-positive waste—actively diverting materials from the waste stream but also removing and salvaging materials that would otherwise be destined for the landfill. In short, a true Living Building is regenerative in that it generates enough benefits to the building’s site, to the project’s community, and to the environment at large to offset any negative impacts that the project may incur. While this may all sound like a tall order, as of October 2016, there were nearly 350 registered Living Building Challenge projects comprising more than 10 million square feet of gross building area in 13 countries around the world.

The Living Building Challenge consists of seven performance categories, deemed “Petals” based on the metaphor of a flower that efficiently gives back more than it takes. The seven Petals are titled Place, Water, Energy, Health & Happiness, Materials, Equity, and Beauty, each of which are subdivided into 20 Imperatives, or areas of focus. These petals can be, and have been, applied to all building types, sizes, and locations. In order for certification to be achieved, there are two basic rules. The first is that all 20 imperatives within the seven petals are mandatory. There are not different levels of certified buildings—either a building qualifies or it doesn’t. The second rule is that Living Building Challenge certification is based on actual building performance when constructed and occupied, not modeled performance. Therefore, projects must be operational for at least 12 consecutive months prior to evaluation to verify compliance.

The ILFI has determined that, while achieving Living Building Certification is the ultimate goal, recognition can be garnered for meeting the Imperatives of multiple Petals, which is seen as a significant achievement by itself. Therefore, Petal Certification is available when at least three of the seven Petals are achieved, provided that one of them is either the Water, Energy, or Materials Petal. Similarly, ILFI is willing to recognize and certify buildings that qualify as net-zero energy buildings based on ILFI’s definition: 100 percent of the building’s energy needs on a net annual basis must be supplied by on-site renewable energy with no combustion allowed. There are also some other basic requirements related to different Imperatives as part of this certification. As with all Living Building and Petal Certifications, NZEB certification is based on actual performance rather than modeled outcomes.

While the actual certification requires documented performance after occupancy, the only way to get there is to design the building to that level in the first place. That means using many of the same principles and the same computerized BIM tools as we have seen in the other levels of performance discussed. That is good because design professionals have access to everything they need to create Living Buildings. It does mean, though, that some additional commitment is needed of our talent, skill, and plain perseverance to the use of these tools to reach beyond conventional thinking and dig into more details than may be typical. That effort will be worthwhile in the end when, in every respect, the maximum positive outcome is achieved for the building, the people who use it, and the community where it is located.

Conclusion

Architects, engineers, and other team members use an array of design tools to satisfy a full range of criteria for new and renovated buildings. For an increasing number, that includes the use of BIM to create better designs, higher building performance, improved cost control, and more efficient workflow processes, not only in design but also in construction. The data in a BIM model forms the basis for analyzing and documenting a building either directly or in concert with other computer software. This is extremely evident when looking at energy performance and green and sustainable building design. When design teams and owners determine the level of performance that is being sought, from code minimum to net positive, then the proper use of the right software will not only help achieve those levels, but it can also truly enhance the whole process.

Peter J. Arsenault, FAIA, NCARB, LEED AP, is a practicing architect, green building consultant, continuing education presenter, and prolific author engaged nationwide in advancing building performance through better design. www.linkedin.com/in/pjaarch

Vectorworks, Inc. is the developer of Vectorworks software, a line of industry-specific CAD and BIM solutions that help more than 650,000 visionaries transform the world. www.vectorworks.net