Healthy hospital success: Sustainability
With hospital projects, it is imperative that engineers get everything exactly right—after all, the lives of patients treated in the health care building may depend on it. Sustainability, energy efficiency, and intelligent buildings are discussed.
Richard Heim, PE, LEED AP, Mechanical Project Engineer, RMF Engineering Inc., Baltimore
Tim Koch, PE, LEED AP, Electrical Engineer, HDR Inc., Omaha, Neb.
Nolan Rome, PE, LEED AP, Senior Vice President, ccrd, a WSP | Parsons Brinckerhoff Co., Phoenix
Raymond Schultz, PE, Project Engineer, CannonDesign, Grand Island, N.Y.
Kunal G. Shah, PE, LEED AP, RCDD, President, PBS Engineers, Glendora, Calif.
Tommy Spears, PE, Vice President of Design Solutions, TME, Little Rock, Ark.
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 a hospital?
Rome: We have recently employed heat pump chillers and group-source heat pump technologies to reduce the energy footprint of our hospital designs. A hospital is one of the few building programs with simultaneous heating and cooling loads in all seasons, allowing us to harvest the heat being removed and use it for reheating and to produce hot water, thus reducing the cost of utilities and achieving both natural gas and domestic water make-up savings by not using cooling towers to reject heat. We have not yet designed a net zero hospital, but we are using PVs and solar water heating on a hospital project that is the closest thing to net zero energy that we have done.
Spears: We often specify high-performance systems for the majority of our health care projects, including heat pump chiller heaters, advanced building automation controls, and sequences of operation to reduce overall energy consumption. However, even though the design is intended to be high-performing, it doesn't always function that way once the facility is in operation. On a recent project for a hospital in Florida, TME provided commissioning services after the high-performance design was completed but did not meet the Energy Star goal of 75 that was set by the owner. After TME was engaged and implemented several zero-capital improvement projects, the Energy Star rating increased to a 97, making it one of the most efficient facilities in the nation.
Koch: Most of the hospital projects we have designed in the last several years have implemented or evaluated the implementation of a heat-recovery chiller system. Hospitals are an ideal application for a heat-recovery chiller due to the airflow air-change requirements in rooms and the need to reheat this air in interior spaces while requiring cooler supply air for exterior spaces. Hospitals also operate 24 hours a day, which increases the payback. These systems are especially beneficial if there is a year-round cooling requirement such as a main data center in the hospital.
Shah: There is a growing trend to explore the feasibility of net zero; however, for a hospital function it is very difficult to achieve. The consumption level is very high, which makes it difficult to produce that high of energy to offset. Our team has done numerous studies and provided options to help achieve net zero energy for office-building and commercial function. Implementing HVAC strategies and on-site renewable energy systems are the foundations to developing an appropriate system.
Heim: RMF recently specified magnetic-bearing (frictionless) chillers in a hospital central plant. The chillers have an excellent part-load efficiency, which is often where the central plant is operating. The downside is that they are extremely sensitive. There was certainly a learning curve, but after adjusting several setpoints, we have seen the energy benefits of the system. Building owners have often requested energy wheels on AHUs, which due to the frequent high requirements of OA in hospitals allow another opportunity for energy savings.