Engineering flexible office buildings: sustainable buildings/energy efficiency
Office buildings need to have the ability to accommodate myriad types of businesses and activities to meet the needs of tenants. Here, engineers with experience on such buildings share their knowledge, lessons learned over the years for sustainable buildings/energy efficiency.
Cory J. Abramowicz, PE, HBDP, LEED AP, Associate, ESD (Environmental Systems Design), Chicago.
Matt Chandler, PE, LEED AP BD+C, BEAP, Senior Engineer, KJWW Engineering Consultants, St. Louis.
Andrew B. Horning, MS, LEED AP BD+C, Associate & Project Manager, Bala Consulting Engineers Inc., King of Prussia, Pa.
Julianne Laue, PE, LEED AP, BEAP, BEMP, Senior Energy Engineer, Mortenson Construction, Minneapolis.
Matthew Pastore, CxA, Director of Design-Build Services, GHT Ltd., Arlington, Va.
John Yoon, PE, LEED AP, Lead Electrical Engineer, McGuire Engineers Inc., Chicago.
Mike Walters, PE, LEED AP, Campus Energy Market Leader, MEP Associates LLC, St. Paul, Minn.
CSE: Energy efficiency and sustainability are often a request from building owners. What net zero energy and/or high-performance systems have you recently specified on office buildings (either an existing building or new construction)?
Abramowicz: In a recent net zero energy office building we designed, we used UFAD as the primary air-distribution method, ground-source heat rejection, a photovoltaic farm on the roof/surface decks to generate power, and solar concentrators for hot water. It is important to first explore and apply all possible passive strategies including situational, geometric, and shading opportunities. Another important component is educating the client on how to reduce operational loads.
CSE: Many aspects of sustainability (power, HVAC, etc.) require the building facility team to follow certain practices to be effective. What can an engineer do to help increase the chance of success in this area?
Laue: Communication and training are vital to helping the building facility team be successful post-construction. The facility team needs to be involved early in the design through commissioning.
Chandler: It is important to educate the owner on the operational impacts of the systems designed for their facility. They need to understand how each system operates and how it may differ from other buildings. For example, projects using heat-recovery chillers for energy savings will often have heating water-supply temperatures around 135°F to 140°F. This is very different from an older facility where heating water-supply temperatures of 180°F or even 200°F were used. Educating the owners on why their building systems operate differently from what they are used to goes a long way to ensure they don't implement operational changes that will be detrimental to the energy-saving features provided.
Abramowicz: An important aspect of ensuring the sustainable designs are implemented and remain operable throughout the building's life occurs during the final project turnover process. During this stage, active communication between the design team and building facility team is critical to the overall operation and maintenance of the system. As the building and MEP systems are designed, design considerations are made to increase efficiency, prevent issues, and improve ease of future maintenance. Occasionally, a building facility member will override an operation setting with the understanding the system operates similar to the system of a previous building. This, however, can present an issue as it digresses from the original operation intent. If an open dialog is established between the building facility team and design team, issues can be resolved while still maintaining the designed sustainability goals. Another aspect of sustainability is actively repairing and maintaining the building systems.
CSE: What types of renewable or alternative energy systems have you recently specified to provide power for such projects? This may include PVs, wind turbines, etc. Describe the challenges and solutions.
Abramowicz: PV panels are an intriguing implementation to a building's renewable energy system. However, due to the nature of typical high-rise buildings, designing for the space and location while still providing a large impact on the building energy use is challenging. High-rise buildings are typically designed as several floors with small footprints stacked on top of each other. Conventional PV panels, typically installed on horizontal surfaces, aren't suitable for these applications due to the small building footprint. This often results in either implementing the PV panels vertically into the building's architecture or implementing PV glass in place of the standard glazing in the building's façade.
CSE: What types of water reuse or conservation systems have you specified into office buildings? Describe their performance and savings over the course of 1 year.
Chandler: Water-conservation techniques are commonly implemented in new construction and renovation projects. Water collection and reuse systems are much less common because, in many areas of the country, they aren't supported by economic analysis. When we see these features in buildings, it is typically at the request of an environmentally conscious owner despite the lack of support by lifecycle costs.
CSE: What are some of the challenges or issues when designing for energy efficiency for office buildings?
Abramowicz: One of the biggest challenges for the project team is analyzing whether the overall expense of the more energy-efficient systems will be outweighed by the marketability of the system being installed. As the project's design progresses, the project's team has to assess whether what is being added to the project will pay off in energy savings, in marketability to potential tenants, or in marketability of these systems that extends beyond the building to the rest of the community. Another key consideration is the overall ownership time frame for the client. If the client is looking to own the building for 30, 40, or 50+ years, the allowable payoff time frame could be more acceptable because the owner will repair and maintain the building for this duration.
CSE: What types of high-performance and/or smart buildings have you recently designed for an office-facility client? Describe the facility.
Abramowicz: One of the primary focuses of our business is intelligent buildings. We are excited by the maturation of building and peripheral technologies and the possibilities these present to our clients when systems are properly stitched together. We believe engineers need to do a better job at educating clients on what an intelligent building is and avoid using words like "smart" and "green." Too often, we encounter clients that are disillusioned and believe that an intelligent building is a supercharged BAS that has some metering, lighting control, fault detection, and dashboard layered on it, whereas in actuality, there are 15 or so core systems that together make up an intelligent building. It is often not possible to establish a business case to integrate all these systems together at once to achieve an ultimate end outcome when things continuously evolve. We work with our clients to establish a long-range vision and master plan that begins with an integrated and converged network that is open, scalable over time, and doesn't preclude the integration of future technologies that are yet to be developed. We believe that many current systems and providers who do not subscribe to this will be leapfrogged by the rapid developments in this area.
CSE: Office-building occupant health has been studied frequently. What type of HVAC, daylighting, or other methods are you including in your office building design to meet these "healthy space" requests?
Laue: Having buildings that feel open, have access to natural light, and allow occupants to experience an outdoor environment while indoors are key drivers in defining occupant health and wellness. Lighting systems that mimic natural light and dim appropriately as daylight levels change are important. HVAC systems that are thermally and acoustically comfortable as well as provide fresh air are key. Engineers have been providing these systems for a long time and, in recent years, have been doing more to highlight how the engineered systems are making occupants "healthy." Healthy spaces are required by codes, but occupants don't always realize the benefits of the engineered systems. The latest methods employed by engineers are not in the design of their systems, but in the discussion of their systems ... not just during design, but during occupancy.