Using energy wisely is a cornerstone of sustainable design. LEED recognizes the importance of optimizing energy performance by allocating the greatest number of potential points within this category. In general, points can be earned through efficient design, use of renewable energy, deliberate mechanical and electrical system selection, and proper commissioning and monitoring. Because energy savings translate directly into operational savings, Energy and Atmosphere credits typically have the highest payback of all LEED credits for the owner. Many opportunities exist within this category for synergistic design, and it is best to get the engineering team engaged early in the design process to encourage a successful, integrated design process.
MultiCare Good Samaritan Hospital has set aggressive energy conservation goals that will result in the Dally Tower being one of the most energy efficient health care facilities in the country. Statistical data shows that a typical hospital designed to code in the Northwest has an average energy use index (EUI) of 263 kBtu/sf-yr. GSH is predicted to achieve an EUI of 145 kBtu/sf-yr, a 45% savings compared to a typical hospital. Early in the design process, the entire project team participated in design meetings with an agenda of gathering all ideas for how to achieve the goal. Building energy simulation software was used to determine which efficiency measures would meet the project goals.
The following is a summary of the major efficiency measures that were included in the project.
High performance glazing, external wall thermal resistances beyond code requirements and external shading have all been employed to reduce loads and energy consumption of the HVAC systems.
Where possible, lighting power density has been reduced and occupancy sensors are used to reduce the building lighting demand. Light shelves have been employed in patient rooms to minimize the amount of artificial light needed during the day.
Two 1,500-ton, high efficiency variable speed chillers provide cooling for the building. Also, pressure independent control valves and high efficiency variable speed pumps are used on the chilled water system to optimize the efficiency of the chillers and minimize pumping energy.
Heating and Ventilation
Typically the two largest sources of energy use in a hospital are fan and heating energy. The Dally Tower has special equipment and controls that protect the health and well being of patients and staff while reducing both fan and heating energy by over 30%. Because all areas of a hospital require pressure relationships in order to minimize cross contamination and protect the health of patients and staff, constant volume ventilation systems are typically used to serve hospitals. Good Samaritan Hospital installed special controls to reduce the volume of air being supplied which results in up to 30% fan energy savings. Supplying less air also means that less air needs to be heated and this reduces heating energy by up to 30%.