Julia Rogers
by Julia Rogers
Healthcare energy consumption is at all all-time high. The average hospital uses three times the energy of a typical commercial building. A study in 2013 demonstrated that healthcare facilities spend $8.8 billion per year on energy consumption. Retrofitting allows for energy to be able to be distributed with the highest of efficiency while reducing costs dramatically[1]. Growth in hospital energy consumption worldwide is projected to continue at an annual rate of 1.4% until 2030.
Reducing excessive energy costs requires a comprehensive approach toward hospital design and a dedicated team to review the operation after occupation. Vanderweil has found that a four-step process ensures successful energy design for healthcare facilities:
Step No. 1. Set great goals! Setting the right goal is crucial for an efficient project. The Energy Use Index is one metric, but there are many more options that can be more appropriate for a hospital such as: cooling (sf /per ton); heating (therms/required by HDD); and energy/per person served. Every goal should be made with the climate and program in mind first: Boston and San Francisco require different amounts of energy (nearly 15% difference, on average). A 24-hour facility requires much more energy than a 10-hour clinic.
Step No. 2. Reconsider the program. Will you have an OR? Operating rooms account for 2x to 3x the energy used in any other space program in the hospital. How high will you go? Air Changes can be nearly 4x as high in an in-patient procedure room as they are in an out-patient room. Operations in hospitals often exceed the minimum ACH; however, more air changes does not equal cleaner air. How much research? Fume hood airflow and pressurization are higher in any room housing chemical research. How much equipment will you use? 24-hour equipment use contributes to a heating load that requires additional heating. Consider reduced operational schedule for equipment rooms or sharing equipment across departments (instead of redundant plug use) and incorporating low-energy equipment and auto-shut offs.
Step No. 3. Use energy efficiently (and reuse it!). Waste heat can be mitigated with efficient energy recovery systems, such as enthalpy wheels and glycol loops that absorb energy where it would otherwise be wasted into atmosphere. Consider low-reheat strategies: Delivering primary air at a neutral temperature avoids the need to add heat to prevent overcooling the space at low cooling loads, but it requires the entire space sensible cooling load to be offset by the chilled beams (the primary air provides no space sensible cooling). Separate the ventilation from the heating and cooling, where appropriate. Savings can be achieved when reducing the ventilation to minimum required loads, while still maintaining comfort through in-zone supplemental cooling and heating units.
Fuel the building optimally: 1) Renewable energy sources such as solar PV, wind, and/or geothermal; or 2) central heating and cooling plant with efficient equipment that can serve multiple buildings. Consider a fuel cell: Combined heat and power (CHP) fuel cell systems, including microcombined heat systems, are used to generate electricity and heat. The system generates constant electric power (selling excess power back to the grid when it is not consumed), and at the same time produces hot air and water from the waste heat. The waste heat from fuel cells can be recovered efficient in winter and summer.
Step No. 4. Review! RGV360, a new Vanderweil program, helps to identify where design strategies are optimized or underutilized in buildings after occupancy. These inefficiencies occur regularly, and we have found that a review of each building can result in savings with minimal effort, by calibrating sensors or opening dampers that have gone into a by-pass mode. Commissioning efforts have shown a 15% return-on investment (ROI) for hospitals[2]. These results stem from HVAC controls adjustments (very low investment), through sealing ducts, and reducing the supply air in unoccupied modes, which are regularly set higher than is required.
Healthcare is an area with the potential for new leadership in low-energy design; design teams can help owners understand how to achieve better building comfort with increased client satisfaction, while decreasing excessive energy costs.
Julia Rogers, LEED AP+ BD+C, is a sustainable design leader at Vanderweil Engineers in Boston.
[1] American Energy Assets “Healthcare Energy Assessment, 2014.”
[2] Energy.gov/Energy “Efficiency and Existing building commissioning, 2014”
