The National Institute of Mental Health (NIMH) statistics show that nearly one in five U.S. adults live with a mental illness, and that one quarter of those adults suffer from Serious Mental Illness (SMI). These numbers from 2019 are expected to rise due to stress and uncertainty related to COVID-19, increased unemployment, and substance abuse. Southern Maine Health Care (SMHC) partnered with Maine Behavioral Healthcare to repurpose decommissioned inpatient med-surg and critical care beds at their Sanford Campus to expand inpatient behavioral health services to address the growing need for care in the communities south of Portland, Maine.
The building and the existing infrastructure presented some opportunities for substantial cost savings by re-using the mechanical, electrical, and plumbing systems. The 10’-0” floor-to-floor heights on the first floor and only 9’-2” clear to the underside of the structure in the corridors, challenged the design team to find a replacement for the existing window units, presenting several challenges to patient safety. The team determined the best solution was providing new chilled beams to provide heating and cooling to the new in-patient units that are ligature resistant and energy efficient and would allow the team to re-use the existing ductwork, already sized for 100% outside air for the required air changes.
A typical four-pipe system uses double the amount of piping of a typical two-pipe system, so a four-pipe configuration has a higher construction cost due to the increased material needed. A typical two-pipe system is cheaper because it requires less piping and valves; however, it usually requires a manual or automatic change over between the central cooling and heating plants. Where there were existing hydronic heating and cooling piping systems in the areas being renovated, both configurations were considered. Upon further research, it was discovered the chilled beam manufacturer offered an option where they could provide a stand-alone valve control module for the chilled beams that could be connected to both the heating and cooling system (four connections on one side) and the inlet and outlet connections to the chilled beams. This allowed most of the existing piping systems to remain. The new piping that was required to be replaced and re-worked was limited to a single supply run and a single return run of pipe from the control module to the beam. Since these modules can be located away from the beam, the locations were coordinated to limit the amount of hydronic heating and cooling piping required.
The overall installation and operational cost of a chilled beam system can be less than a traditional fan coil or VAV system. Since the chilled beams can provide airflow from a dedicated 100% outdoor air unit, less total air is required to achieve the minimum outdoor air change rate called for by the Facilities Guidelines Institute (FGI) and ASHRAE 170 Standard. Since this airflow is approximately 60% less than a typical variable air volume system, the size of the supply ductwork mains can be smaller. This smaller ductwork translates to less material and lower labor costs for installation. The existing air handling systems serving the areas that were renovated for new inpatient space were previously fan coil systems with 100% outdoor air handling units. In this case most of the existing supply and exhaust ductwork mains were able to be left in place and be re-used, leading to reduced construction costs.
The smaller ductwork runouts to the beams aided in coordination with existing structural clearance and architectural ceiling layouts. A chilled beam can be installed within ceilings with 10 inches of space. With the low floor to structure heights here, the low profile of the chilled beams helped contribute to meet or exceed the minimum ceiling heights within the inpatient areas.
One of the biggest benefits of chilled beams is their energy efficiency advantage over traditional air heating and cooling systems. Only ventilation air is required to be ducted to the chilled beams to meet the required outdoor air change rate for the room as required by the FGI and ASHRAE 170 Standard. In a typical VAV system that uses airflow to heat and cool the space, this airflow could be more than 60% higher than the minimum required airflow. This results in needing a larger central station air handler with larger fans that consume more energy. The central station air handler would also require larger capacity heating and cooling coils to heat, cool, and dehumidify the larger air volume. The electrical costs for a fan coil unit system are higher than a chilled beam system because every fan coil terminal has a fan motor where chilled beams do not have any fans and do not require electricity.
Maintenance for the HVAC systems must be considered, especially in a behavioral suite. With a typical fan coil unit system, the fan coils need regular maintenance, including changing filters, cleaning coils, replacing fan belts, condensate pumps, and cleaning condensate traps and drip pans. Ideally, this service would happen on an annual basis. With chilled beams the frequency of maintenance and associated costs are lower than a fan coil or variable volume air system. Chilled beams do not contain fans, motors, or dampers that require changing or lubricating, and most chilled beams do not have air filters that require changing. When designed and controlled correctly, the cooling coil does not produce any condensation so regular cleaning and disinfection of the coil is not needed. The typical recommended preventative maintenance for a chilled beam is to vacuum the coil every five years. In a patient room setting it is recommended that this is done more frequently. However, the amount of time, effort, and cost is much less than conventional systems and this will decrease the amount of tools and objects maintenance personnel need to bring into high-risk areas.
The patient rooms are a high-risk area for patient self-harm due to reduced staff oversight to respect a patient’s privacy as they change and/or use the bathroom. They require a high level of ligature resistant design and coordination of all fixtures and furniture to minimize the risks to patients. The design created two zones within the patient room to maximize ceiling heights where the chilled beam, lights, and access panel were in a monolithic dry wall ceiling. The second zone at the entry of the patient room, including the patient toilet/shower room, had a lower ceiling to accommodate the ductwork serving the patient room.
The chilled beams are often hung from threaded rods from the structure above which in crowded ceiling plenums can present challenges to coordinating all the systems. The sizes of the chilled beams, some as long as 8’-0” are new elements to coordinate.
When all aspects of the design are fully analyzed and standards and guidelines are met, the existing mechanical systems can be adapted to meet chilled beam requirements. Most importantly, patient and staff safety can be addressed. Therefore, chilled beams are an excellent energy saving alternative to a typical VAV or fan coil unit system in a behavioral health unit.