Performance Based Modeling

According to the EIA, buildings consume nearly 50% of the energy generated in the U.S. and produce 44% of the carbon emissions[1]. Certifications and codes help to drive reductions in the built environment, but as we look to meeting the energy needs of the future, designers can take a leadership role in doing our part for the industry.

Reducing energy use in our buildings can be done in a number of ways, but taking a critical look at the beginning of design allows for maximized impacts. Previously energy modeling was a skill that was reserved for engineers, and often involved complex details and a substantial amount of time. As an alternative, performance based models, where conservation targets are considered as soon as pen hits paper, is gaining popularity.

Building orientation and massing provide important opportunities for reducing energy in early design decisions. While designers often use rules of thumb, modeling allows you to see the direct impacts of adding shading devices or increasing the amount of glazing on a façade. It also becomes a component of the integrative design process, ensuring synergies between building systems are optimized.

Traditional energy modeling requires building improvements in later stages that then compete for priority. Early modeling of energy allows for flexibility and innovation by analyzing the impacts of various design scenarios and learning from each one. Taking it a step further, the process can be enhanced when coupled with benchmarking or Measurement and Verification once a building is completed, allowing the owner to ensure that the building is performing as designed. The analyses can also assist in maximizing daylighting by identifying over and under-lit spaces and priorities the type of shading and glazing needs for each façade. According to recent studies by Harvard School of Public Health, daylight has significant impact in the thinking and performance of students. There is a significant correlation between daylight in classrooms and student performance, particularly in material ready assessments as well as increased alertness and physical activity.

The continuous improvement process allows both the designer and the building to raise the bar of performance and track it over time. The result is schools that save on operation and maintenance costs. According to a survey from Turner Construction, sustainable schools can achieve direct savings of $12 sq. ft. going directly back into the school in the way of energy savings, lowered water costs, improved teacher retention and lowered health costs all for an increased cost of less than 2% more than conventional schools (approximately $3 per square foot) to make them green[2]. 

[1] U.S. Energy Information Administration (2012).

[2] “2005 Survey of Green Buildings,” Turner Construction. Available at: http:// www.turnerconstruction.com/greenbuildings

Integrative Design

Sustainable design benefits from a holistic, or integrated approach, that creates opportunities for the integration of a wide variety of systems and approaches. Changes in technology in both areas are driving the need to integrate a wide range of systems creativity in order to optimize outcomes for the client.

Over the past several weeks, I’ve been asked about our approach to integrated design several times. Integrated design can be defined as: involving all design disciplines, starting from project inception through construction, rather than the typical linear structure with successive contributions. The process allows for systems-thinking rather than the architect and client agreeing on a design concept and then asking mechanical and electrical engineers to suggest appropriate systems at a later point. Major savings can be achieved in design if we think about concepts such as furniture, energy efficiency, and lighting and their impact on one other early while the design is still flexible enough to consider synergies. 

An integrated process is particularly important when it comes to sustainable design and realizing deep reductions in energy and water use. This is a practice that is ingrained in the process of how we work and further enhanced on projects that involve our design team in addition to our internal mechanical, electrical, plumbing, and civil engineers. Furthermore, involving the energy modeler and commissioning agent from start ensures that all possible options are assessed from envelope to lighting to mechanical systems before final decisions on layout are made.

A recent example of how this played out in one of our projects was during a charrette where we invited all of the disciplines to set goals. After some of the preliminary design concepts were presented, the mechanical engineer pointed out that there was a large amount of glass on the southern exposure of the building. Having the engineer in the room allowed us to make some quick changes that included adding shading and discussing high performance glazing, so as to not over size the mechanical systems as a result.

To help us achieve our energy goals using an integrated approach, we use performance-based modeling through a combination of BIM, energy, and water software tools. This approach allows for fast and simple inputs in the early design stages to determine the approximate load compared to similar buildings. The model can then be re-run throughout the design process to assess impacts from various scenarios and design changes, which can lower both capital costs as well as facilitate project delivery.

The process requires various disciplines and breaks down silos between disciplines, and therefore necessitates more effort on the front end of a project. In order to be effective, there must also be feedback loops so that integrated design is more than just a conversation. The charrette and subsequent progress meetings should be multidisciplinary as well and the resulting stronger team can prove meaningful beyond just the project scope.