Performance-based energy analysis produces valuable metrics that can influence design decisions early in the project, when design changes are easier and less costly to incorporate. Leveraging metrics obtained from a whole-building analysis, such as energy use intensity (EUI), solar production potential, and HVAC costs, can yield better performing buildings that lower operating costs over the life of a building, respond to an evolving climate and respect our environment.
The common impasse facing project teams is getting accurate energy use data early enough to inform decisions around building scale, massing, orientation, and façade details. To mitigate this, SMRT uses an integrated approach in our standard design workflow that offers a predicted energy use intensity (pEUI) analysis through project completion, starting on Day One of the project.
Figure 1: Day One energy analysis shifts decision-making earlier in the process
Focused Building Component Analysis
In contrast to the traditional single source performance-based analysis, a more useful approach focuses on multiple specific, key design criteria. For example, studying a building’s orientation takes little detail and simply involves using already-developed basic building masses rather than a detailed model. Using solar radiation tools, we can quickly compare multiple building mass options to determine the design that optimizes solar exposure for the specific building use.
Taking this a step further, we then begin to develop the building façade to evaluate solar heat gain/loss and natural daylighting. Design teams quickly weigh various shading approaches, isolated façade orientation and different glazing configurations, thereby generating helpful data that can affect other critical early design decisions. The emphasis here is early, as this analysis allows for rightsizing mechanical systems that will serve the building over its lifetime.
A Simultaneous, Iterative Approach
To bridge the gap between Day One studies and more detailed analyses, our teams run a series of simultaneous analyses on a range of design details — for both known and unknown scenarios — for each component of a design.
Let’s look at a scenario involving just one building component. At the beginning of a project every building component used in an energy analysis has a range of variables associated with it that carry workflow implications. For example, will the wall assembly be an R-38 or R-45, or will the building plug-load be 1.5 Watts/ft2 or 0.7 Watts/ft2? This type of question can be applied to more than 20 different building components, with each offering between 5 and 10 design variables.
It is easy to see how picking the perfect combination of variables for all the components on Day One is equivalent to finding a needle in a haystack. Furthermore, a decision concerning one component will influence another; while Mechanical System A might be optimized for an R-45 wall assembly, Mechanical System B might be best for an R-38 wall assembly.
Figure 2: Simultaneous simulations enable designers to quickly analyze several design options at once, ensuring the best decision is being made based on operation cost, construction cost and maintenance.
Our approach is to simultaneously analyze all these components and their variables, thus helping us to identify the strengths and weaknesses in the individual components as well as the coordinated, integrated design. As the project moves through design development, the range of options can be narrowed to more precise solutions, ultimately providing a final pEUI at design completion. This provides a constant feedback loop of optimization followed by verification and identification of the next component to be optimized.
The iterative process is repeated throughout design phases. As building details are assembled and prepared for the whole building energy use analysis, these benchmark analyses ensure optimization of building systems, saving building owners and tenants operational costs over the life of the building.
Architects and engineers are uniquely positioned to have direct, consequential impacts on the built environment. SMRT sees making a positive impact on the planet as our professional responsibility. As a signatory of the AIA 2030 Challenge, which targets the elimination of fossil fuel energy consumption in our buildings by the year 2030, SMRT integrates informed, energy-reducing choices at every opportunity. To learn more about SMRT’s pre-design energy analyses and our sustainable practices, connect with me via phone or email.