Operating on medical and hospital projects: sustainable buildings/energy efficiency
Larry Anderson, PE, RCDD, CDT, Principal, TEECOM, Oakland, Calif.
Jeremy Jones, PE, LEED AP, EDAC , Healthcare Market Leader, Affiliated Engineers Inc., Chapel Hill, N.C.
Daniel S. Noto, PE, LEED AP BD+C, Healthcare Studio Leader-Southeast Region, exp, Atlanta
Eric Reuther, PE, LEED AP BD+C, Principal, McClure Engineering Associates Inc., St. Louis
Jonathan B. Slagel, PE, LEED AP, HFDP, Principal/Vice President York Office & Healthcare, Barton Associates Inc., York, Pa.
Bill Talbert, PE, BEMP, LEED AP, Senior Mechanical Engineer, MEP Associates LLC, Verona, Wis.
CSE: Energy efficiency and sustainability are often requested by building owners and CIOs. What net zero energy and/or high-performance systems have you recently specified on hospital or medical campus projects (either an existing building or new construction)?
Reuther: On the last couple OR additions, we have been able to design the ORs with individual AHUs. A separate ventilation unit with a desiccant wheel provides very dry air to each OR AHU. This allows each OR unit to only cool the air enough to satisfy the space load, eliminating a large amount of reheat and producing substantial energy savings for the facility.
Talbert: Air-side energy recovery, active chilled beams, and dedicated heat-recovery chillers are a few systems I have specified on hospital projects. Some areas require high outside-air rates and air-side energy-recovery systems to reduce energy use associated with conditioning the outside air. Chilled beams provide a means of meeting space-cooling requirements while reducing fan energy associated with all air-based systems. Hospitals often have simultaneous heating and cooling loads year-round or for a large number of hours. Heat pumps and heat-recovery chillers provide an efficient means of simultaneously generating chilled water and hot water in lieu of rejecting waste heat.
CSE: Many aspects of sustainability (power, HVAC, etc.) require the building facility team to follow certain practices to be effective. What, if anything, can an engineer do to help increase chances of success in this area?
Reuther: Our approach on projects that we provide commissioning services has been to provide owner training for the facility’s staff. While the contractors typically provide training for the equipment, this training is from the commissioning agent and design engineer, which brings a different perspective to the table. The goal is to help the facility’s staff understand how the system works as a whole rather than just the ins and outs of each piece of equipment. We find that the better the staff understands how the system works, the better decisions they make while operating the system over time. On this same note, it is important for the design engineer to provide good sequence of operations on the drawings to explain the intent of how the system actually works. Putting these on the drawings makes a good reference point for troubleshooting the system later on.
Jones: It all comes down to education. Hospital facility directors are historically conservative for all the right reasons. They are, in a very real way, responsible for the comfort and safety of patients. They are often reluctant to try new or unfamiliar systems because they at least know how to deal with what they already have. If we agree together to move toward alternate systems that are more energy-efficient, it is our responsibility to be fully transparent with the benefits, the challenges, and to help them through learning to care for their new system. We can also arrange site visits to similar installations of the newer technology, and then get out of the way and let them ask all of their questions without a perceived bias.
Talbert: Identifying sustainability goals and performance targets early on in the design process and engaging everyone on the project team in exploring opportunities and decision making are key to successfully implementing high-performance strategies. The synergies between different elements and systems in the building require consideration of how different systems impact each other. Communicating benefits beyond energy savings, such as installation cost savings, construction efficiencies, and comfort improvements, will help the team understand all of the potential benefits associated with a specific strategy.
CSE: What types of renewable or alternative energy systems have you recently specified to provide power for such projects? This may include photovoltaics, wind turbines, etc. Describe the challenges and solutions.
Jones: While we didn’t use it for power generation, we did implement significant solar domestic hot-water heating on a recent major hospital expansion. The system was able to provide all of the domestic water-heating needs of the expansion as well as backfeed portions of the existing hospital. The system will be leased from the vendor for the first several years and will then be completely turned over to the hospital for the remainder system’s lifecycle.
CSE: What types of water reuse or conservation systems have you specified into hospital or medical campuses? Describe their performance and savings over the course of one year.
Reuther: In some cases, we have specified low-flow plumbing fixtures. These can save around 20% of water usage compared to typical plumbing fixtures.
Talbert: There are many connections between HVAC-related energy use and water use in a hospital that provide opportunities for reducing water use. Cooling systems that rely on cooling towers for heat rejection use a tremendous amount of water, often eclipsing the amount of direct water use at fixtures. Improving cooling efficiency reduces the amount of heat rejection, thus the amount of water used for make-up. Using systems such as heat-recovery chillers reject heat for use in building heat and eliminate the need for cooling towers. Geothermal-based heating and cooling systems eliminate the need for evaporative heat-rejection systems and drastically reduce water use. Where evaporative heat rejection is used, make-up water requirements can be reduced through drift eliminators and controlling the cycles of concentration. In addition, cooling coil condensate capture and reuse for cooling tower make-up water can further reduce water demands. Air-side energy-recovery systems that recover latent heat reduce humidification loads and the associated make-up water.