EXP selected for the first design phase of the new Île d’Orléans cable-stayed bridge
(This article was originally published in the June 2020 issue of the Florida Engineering Society Journal)
Amy Pastor, PE, CxA, LEED AP I Director of Commissioning and Sustainability, EXP
As a LEED professional and long-time energy modeler, I am frequently asked about ways to design a building more efficiently to result in targeted energy reductions and complement sustainable best practices. In these conversations, I urge the dialogue to focus on a building as a portfolio of assets instead of a single entity. When considering the ideal solution for better buildings, I have found the best answer is not easily acquired. It requires professionals to dive deeper to deconstruct existing assumptions and processes and seek advanced solutions beyond one product or system to achieve a desired outcome or energy designation. There is no cheat sheet but having an energy professional on your team can help make it feel like one exists.
When it comes to energy, I have found a few necessities to achieve a project’s energy goals. First, include an energy professional early in the design process. Understand the green building rating systems or certification program you plan on applying for and lastly, know your project’s baseline. I have used these as a blueprint to support the certification of 120+ LEED projects and when helping teams strategize effective energy roadmaps for their building’s success.
Early involvement produces results
A building starts with a concept. During early design charettes, architects and owners collaborate on the building’s look, location, orientation, the inclusion of architectural design features and the total building footprint and height. These components are not only relative to the design but significant factors for reducing thermal load and determining a building’s energy baseline. Then involvement of an energy expert at a conceptual level results in early decisions for long-term results, as they can support the design team by providing key insights on potential baseline changes. For example, an energy expert will know how variations on square footage or height of your building impact total energy consumption.
Building certification – There are several certification bodies and rating systems for green buildings including the U.S. Green Building Council (USGBC), National Green Building Standard (NGBS) and Florida Green Building Coalition (FGBC). Each certification body and rating system sets baselines in the form of standards, minimum thresholds or requirements to achieve their plaque or designation. For example, USGBC’s LEED rating systems require a minimum of 40 points across all categories to earn a plaque. Understanding this 40-point baseline is important to develop a LEED checklist to reach your green building goal; otherwise, you aim for the unknown.
Know your baseline – If we focus on the LEED for Building Design and Construction (LEED BD+C) rating system, and specifically, the Optimize Energy Performance credit, a building must show a 6% improvement over the base case to achieve 1 point. The base case in LEED v4 will be determined by ASHRAE 90.1-2010, Appendix G. Knowing your baseline readies your team to systematically target areas for reduction in your design and make project-specific decisions for mechanical, lighting, plumbing and façade systems. A similar process can be used when your rating system or certification body shifts to the NGBS for residential applications or the FGBC for either commercial or residential applications.
Knowledge is power – The value of early modeling is seen in a project’s programmatic decisions and a building’s output. The involvement of energy models has a cascading effect on optimization, efficiency and increased cost savings against the standards. The data from the model is power and we use it to make better decisions for buildings.
From design to efficient operations
New buildings move from design to operational phases similar to the phases of energy management. The three components of energy management are modeling, tracking and reporting. Modeling, which occurs during a traditional design phase, predicts how a building will perform. Tracking starts post-occupancy and is the data collection process. The reporting period is when you prove that the design is as efficient as expected.
A note to keep in mind – at this point, terminology usually transitions. A facility will now say specify a benchmark of their energy use, which is the starting point for all future comparisons. The term baseline is left behind for “benchmark” as the focus shifts to the future performance of a building.
Benchmark appropriately – Benchmarking is a useful method to measure the energy performance of a building over time, motivating long-term performance. There is flexibility in benchmarking unless you are bound by a standard or rating system.
For example, the minimum energy performance prerequisite under LEED Operations and Maintenance (O+M) defaults to a benchmark set by the Department of Energy’s (DOE) ENERGY STAR Portfolio Manager. To date, Portfolio Manager recognizes 80 primary building functions, but only 21 of those types can achieve a score from 1-100. This leaves 75% of buildings in the “other” category – one that has been determined to have an average energy use intensity (EUI) that will cover the other 59 functions.
Good news – The industry, including DOE and the USGBC, has recognized that non-typical buildings cannot be grouped into the “other” category. The DOE’s ENERGY STAR platform offers guidance on how to navigate this benchmarking by comparing to the national median, benchmark against your property’s historic energy performance and setting a target reduction and establishing a benchmark based on the rest of your buildings. I recommend selecting your benchmarking path based on your specific goals and the data available to you.
Advanced metering – A single utility meter at a building is not enough. While this can be used to identify information trends month-to-month and year-over-year, it is difficult to analyze poor performing systems when all you have is the end value.
Metering devices and strategies for collecting data have evolved. It is important to know the total energy use of your building; you also need to carefully select energy-using systems to submeter.
A simple solution is to segregate energy use is by electrical panels. Designing dedicated panels each for lighting, receptacle and HVAC loads allow for metering the panel’s total energy use and then placing that data in respective lighting, plug/process and HVAC ‘buckets.” Another solution is using smart panels, which individually meter each circuit within a panel. The result is more data points for your analysis; however, you reduce the total number of panels in the building, and the number of electrical rooms needed to house these extra electrical panels.
While these perceived straightforward methods give owners a tool to collect energy data, they also have increased construction and material costs associated with them. Instead, a strategic metering plan will offer cost-effective and reliable solutions with faster results. Engaging an energy specialist during design gives this method an even greater chance of success. Energy experts will determine the largest energy users and strategically determine where submeters are necessary to simply and effectively capture the data needed to report on your building’s energy profile. When the metering plans are worked into the construction documents, costs for the meters and ongoing tracking can be transparent, providing the specialist with data necessary to report on the payback period for your metering strategy.
Use the data – Follow through with tracking and using your data to ensure operational efficiencies continue for the building. Your advanced metering strategy can be a powerful tool. Increases in fan energy could be more than an answer to a hot/cold call. It can mean filter replacements are required. Decreases in exterior lighting usage may not be a good thing; broken photocells and timeclocks can be a major safety concern if the exterior building lights are not turning on. If used properly, financial rewards attributed to preventative and predictive building maintenance will be one of the many benefits associated with your strategic metering plan.
Designing more sustainable and energy-efficient buildings will not always be easy. The rigorous process to meet green building and performance management designations requires the early insight of energy experts. With the future looking greener and greener, an energy expert in your corner can help optimize your building with strategic metering strategies and measures for long-term results.