Scott Easton, LC, LEED, AP
This section introduces the subject of engineering dynamic systems and some of the issues encountered in the planning, design and operation of these systems for healthcare facilities. The perspectives taken in this chapter not only address new facilities being designed and built in the 21st century, they also provide a brief look at issues associated with the renewal and renovation of facilities built during the early and mid 20th century which, at times, are viable alternatives to new construction.
Dynamic systems are those that move through the building (water and steam through pipes, air through ducts, electrons and data over conductors). Just as the air we breathe into our lungs and the blood that pumps through our veins are essential in enabling our daily lives, these systems are vital in supporting the mission and strategic vision of the healthcare programs they support. Therefore, they must be robust, reliable, sustainable, flexible and sometimes adaptable to the inevitable changes that occur in providing healthcare services – including research, and education.
Dynamic systems fall into four primary categories in the building design/construction industry:
- Mechanical (HVAC) – Primary thermal equipment and distribution (sources of heating and cooling), ventilation and building pressurization equipment (air handling units, supply/return/relief air ducts), specialty exhaust systems, secondary/terminal heating and cooling equipment (air terminal devices, radiant heating, chilled beams, etc.)
- Electrical – Normal power utility service, primary distribution equipment, voltage transformers, secondary distribution equipment emergency and essential standby power systems (generators, automatic transfer switches, uninterruptible power systems (UPS)), grounding and lightning protection, lighting, fire alarm, metering
- Plumbing & Fire Protection – Domestic water (hot & cold), natural gas, medical gas (oxygen, medical vacuum, medical air, nitrous oxide), sanitary sewer, storm sewer, fire suppression (wet pipe & pre-action sprinkler systems, FM200)
- Information Technology – Voice, data, wi-fi, security, building automation and controls (BAS), nurse call, telemetry, asset tracking, cable TV, and dozens more
These systems often account for an estimated 12-18% of the total gross building area and 30-40% of the total construction cost. In addition, the expected lifespan of systems equipment and distribution varies considerably. Due to higher construction costs of acute care facilities (compared to many other facility types) hospitals are typically built with construction materials and techniques intended to last an extended period of time (50-100 years is not uncommon compared to 20-30 years for other facility types). As illustrated in the chart below, the dynamic systems will need to be replaced multiple times at varying intervals throughout the life of the building structure. Therefore, careful consideration needs to be given to the planning of these systems with accessibility, maintainability and replacement in mind, so that they can be renewed periodically with minimal disruption to clinical programs.Facility Infrastructure Planning
In today’s interdependent world of healthcare, facility planning needs to include a commensurate level of attention to the dynamic systems infrastructure if the resulting plan is to offer the best possible help to the organization. The ability to support new strategic directions, maintain ongoing business operations, and preserve capital all require that the infrastructure be carefully planned along with the site and architecture.
Facilities’ planning has many forms, and to be most successful the infrastructure needs to be addressed along with the overall planning objectives. A brief description of the commensurate level of infrastructure planning for various planning objectives follows.Strategic Planning
Strategic infrastructure planning is part of a strategic facilities plan that addresses site and basic building blocks associated with fundamental functional and/or business units.
The four specific objectives of strategic infrastructure planning are:
- Identify the best use of existing assets
- Identify the potential for reusing those assets in the institution’s vision for itself
- Discover opportunities and constraints created by the systems’ concepts and layouts
- Define broad capital implications of planning alternatives sufficient for commensurate capital planning of revenue, bonding, philanthropy, etc.
An example of this type of planning is helping an existing healthcare institution recreate their campus by defining the highest and best use of the existing facilities. The primary objective is to help the institution avoid expensive, yet low value, investments in intrinsically limited buildings that cannot readily or economically accept infrastructure alterations or changes. Another example of strategic infrastructure planning includes determining when a central utility plant provides the greatest value in lieu of distributed, primary building equipment (chillers, boilers, generators).Tactical Planning
The goals of tactical infrastructure planning are to:
- Develop new and/or facilities renovation concepts to successfully implement the strategic vision
- Establish a sequence of actions that are physically workable for a reasonable level of expenditure and disruption (if renovation is included)
- Establish the probable cost of individual projects so that the annual cash flow of the institution can be planned. The goal is accuracy of an aggregate set of projects, not a single project.
An example of tactical planning can be seen at St. Elizabeth Hospital (SEH) in Appleton, WI. The strategic infrastructure plan resulted in a decision to renew the 80 year old healthcare campus in place to meet the inpatient and ambulatory needs of the next 50 years, in lieu of building a replacement hospital on a new site. A specific renovation and addition strategy was implemented that allowed for phased renovation of intricate buildings and systematic replacement of dynamic systems over 10 years, including an expansion and complete renewal of the existing central utility plant.
.Facility Capital Planning
Facilities capital planning is usually a short term response to the strategic and tactical plan, as well as a response to ongoing needs for maintenance and refreshing.
The content usually required for success is the definition of specific projects in sufficient detail that:
- Capital can be allocated
- An implementation team can be given clear project scope. The goal is to have individual projects estimated to an accuracy that allows implementation within a schedule and budget.
Facilities management is a “real time” activity. It is where physical actions happen. This is fundamentally an implementation activity and any planning is actually logistical and execution management.Sustainable Building SystemsPlanning
Sensible hospital design contributes to an environmentally friendly building that positively contributes to our ecosystem. Hospitals generate hazardous and non-hazardous waste, air emissions, and waste water that can negatively impact our environment. The US Department of Energy (DOE) reports that hospitals exhibit the second highest energy use intensity (EUI) in the building sector. How do engineers formulate innovative solutions that promote environmental stewardship and responsiveness to an institutional mission, yet are sensitive to the bottom line of the healthcare business? The following paragraphs take a brief look at the history of a hospital’s energy use and summarize several issues conscientious engineers focus on as they design dynamic systems. History
With growing attention on climate change and a developing focus on sustainability, it is important to address the energy use of buildings. The DOE estimates that buildings use approximately 50% of the total energy consumed in the US today and produce a similar proportion of greenhouse gases. Hospitals contribute significantly to this figure.
The DOE states that, on average, $2.26 per square foot is spent on energy in healthcare buildings, almost double that of the national average for energy usage in commercial buildings ($1.19 per square foot). The energy used to heat, cool, ventilate and light a hospital contributes the greatest percentage of energy use, followed next by process loads (including kitchens, sterilization and imaging).
Rising energy prices and the increasing energy intensity of hospitals have resulted in escalating costs, with U.S. hospitals spending over $5 billion annually on energy – equal to one to three percent of total hospital budgets, and equivalent to at least 15% of profits. In 2007, the American Society for Healthcare Engineering (ASHE) reported that 91% of hospitals faced higher energy costs over the previous year, and over 50% cited increases in double-digit percentages. Hospitals use 836 trillion BTUs of energy annually and have more than 2.5 times the energy intensity and CO2 emissions of commercial office buildings, producing over 30 lbs. of CO2 emissions per square foot. Addressing the Conservation Challenge
The challenge facing our healthcare industry to reduce operating costs and carbon footprint while providing personalized, patient/family-centered care demands an integrated/holistic building systems approach. The design strategy should start with reducing demand loads by optimizing passive systems. For instance, in a hot, humid climate dominated by the need for cooling, orientating the building with a north-south orientation and properly designed external shading will reduce peak cooling loads, thus reducing the size of mechanical equipment and the cost of energy otherwise required to mitigate the solar heat gain.
Applying engineering rigor (ideation, a first filter of achievable strategies, detailed analysis and performance modeling) in the earliest stages of planning and design to inform sound decision making, followed by initial and recurring commissioning is fundamental in achieving these results.
This approach introduces technical analysis before design begins, informing the process with a creative understanding of the synergies possible in passive and dynamic building systems. Architects and engineers critically assess the interplay of massing, form, orientation, fenestration, envelope, MEP systems, and infrastructure, to yield a holistic solution that responds to the unique qualities of program, bio-climate, and strategic objectives. LEED® certification becomes an outcome rather than a project driver. The following considerations should be evaluated by the systems engineer as early in the design process.
Site Selection/Building Orientation
– Optimized orientation and siting often translate to the creation of dominant north- and south-facing façades, facilitating cost effective solar control strategies related to fenestration design. Initial energy modeling assumptions include optimized orientation and reasonable glazing in the baseline model as a starting point.
· Building Elements
– It is possible to create zones within a hospital that permanently house all major mechanical/electrical/plumbing systems, thus maximizing program space and long term operability.
· Energy Conservation
– Energy efficiency can be thought of as an on-going revenue stream over the lifetime of that investment that actually exceeds what hospitals can get in relationship to making investments in other medical related practices and disciplines. This proves that there is a significant opportunity for actual returns on investment. Why is this investment so important? The following graphic from the DOE demonstrates the need.
- Process Loads – Engineers should work with hospital stakeholders regarding selection of major diagnostic equipment, offering advice about the energy efficiency and potential savings relative to equipment selection.
- Building Envelope – Zone level loads are often about architectural choices particularly in perimeter zones such as patient rooms. Refined architectural design solutions that address fenestration are one of the key envelope design opportunities to avoid creating peak hourly load conditions that drive zone level peak air flow rates (and zone level air system component sizes) significantly above code-required minimums.
- Variable Speed Equipment– Most large chiller plants in today’s hospitals are specified with machines that exhibit excellent full load efficiency. A modest additional improvement in full load efficiency can be achieved using variable frequency drives (VFDs).
- Static Pressure Reduction – A focus on reducing fan system pressure requirements can translate to reduced velocity through filter and coil sections within the air handler, reduced average air velocities in the external ductwork, and improved aerodynamics at duct fittings and take-offs. The reduction in fan power requirement should include specification of premium efficiency motors for all AC motor applications.
- Modular HeatingPlant – Consideration should be given to distributed/modular heating plants in lieu of central steam generation. A modular plant uses condenser modulating boilers to serve low temperature hot water heating loops, dedicated condensing semi-instantaneous water heaters for potable water heating, and significantly downsized central steam generators to meet process steam loads. Process steam could also be served by point-of-use steam generation.
- Renewable energypossibilities – Evaluate potential for alternative energy sources such as geothermal, wind power, solar thermal hot water heating and photovoltaics. Geography and a value discussion regarding first cost vs. operating costs will guide decision making.
- Automated Systems Optimization – Implement a comprehensive “controls” strategy that employs sensor control for lighting and HVAC systems, where allowed by code.
- Thermal Plant Optimization– Unlike many facility types, hospitals have a significant need for simultaneous heating and cooling. Systems approaches that make use of heat recovery (heat generated from producing chilled water) can significantly reduce annual energy costs associated with the thermal plant.
- Heat Recovery Chillers – By designing systems with low temperature hot water for heating and heat recovery chillers for cooling, both needs can be met with a Coefficient of Performance (COP) 50%-100% better than traditional systems.
- Reducing Air Flow Rates– In many cases, energy use is driven by air exchange rates governed by Hospital Standards. A number of approaches to reduce air flow rates and therefore energy usage are utilized today.
- Variable Air Volume(VAV) – While often used in offices and laboratories, the healthcare environment has been tied to constant volume systems for years. Historically, this is due to a need to maintain pressure relationships between adjacent rooms. A number of systems that utilize VAV technology while maintaining pressurization are now being used. There are many functional areas within acute care hospitals where applicable state codes will not allow VAV systems to implement a turn-down ratio of 30% as prescribed by LEED® for Healthcare. Energy modeling assumptions in non-regulated areas such as lobbies, waiting areas, and administrative offices should be prime targets for VAV systems and potentially operable windows, if appropriate based on local climate.
- Dedicated Outdoor Air & Heat Recovery– Use of 100% outside air VAV systems that are equipped with air-to-air heat recovery wheels, coupled with terminal heating and cooling units will reduce fan energy.
- Chilled Beams– In climates where more air is needed to meet the heating and/or cooling loads than what is required for ventilation, traditional air-based systems may not yield the most energy effective solutions. Decoupling ventilation requirements from the need for heating and cooling for thermal comfort creates opportunities for a number of alternative HVAC strategies. Chilled beam technology is one approach that can significantly reduce airflow, cooling and reheat requirements, while maintaining appropriate temperature and pressurization levels. Only the minimum (code required) amount of conditioned (tempered and humidified/dehumidified) outdoor air is delivered to each space. The additional air exchanges necessary to meet the total ventilation requirement are achieved by inducing secondary air flow over non-condensing cooling coils located within the room diffuser (chilled beam), with no additional fan energy.
Using water as the primary means for heat rejection (in lieu of air) significantly reduces fan energy and the size of air handling units and ductwork needed, thus reducing the amount of space required above ceilings and in mechanical equipment rooms. In some instances this even results in reduced floor-to-floor heights. All of this translates into opportunities for reduced construction and annual operating costs.
State Healthcare agencies are likely to exercise caution before allowing a new technology to be introduced in a hospital setting. Therefore, it is important to engage officials early in the design process and provide sound, engineering justification including lab test results, technical papers, ASHRAE committee reviews, etc. It is also important to note that while many healthcare institutions are on the cutting edge of technology, they do not necessarily want to be the first to try something new. Other building types often provide the testing ground for new technologies and the data needed to demonstrate their safety and applicability in patient environments.
- Operating Room(OR) Airflow Reductions – Historically, ORs have operated at 20-25 air changes per hour continuously, whether the room is in use or not. Often, it is allowable to reduce these rates significantly (less than 8 air changes per hour) during idle times, while maintaining necessary space pressure relationships and temperature levels. The viability of this scenario largely depends on the trauma level and types of procedures being performed. How quickly the room needs to come up to “occupied” status is certainly a contributing factor.
- Water Conservation– Healthcare facility water use varies widely depending on type, size, geography, and water use/equipment practices. A water use study published by the Green Building Council in 2002 showed a range of water use from 68,800 to 298,000 gallons per year per bed for hospitals in the range of 133 to 510 beds. The following graphic indicates that hospitals typically have the following broad breakdown of water usage.
There are a number of alternatives/approaches that could be utilized to reduce water usage. Following are a few examples that have been used.
- Plumbing Fixtures
- Dual flush water closets
- Low flow (reduced flush) fixtures
- Sensor operated fixtures
- Collection and Reuse
- Storm drainage
- Subsoil drainage system effluent
- Air handling unit condensate
- Graywater reclamation
Sensitivity to infection control issues may drive feasibility of some of the above reuse proposals, but each should be discussed with the Environmental Health and Safety organizations within the hospital and/or local authorities.
Creating Healthy/Healing EnvironmentsReducing Nosocomial Infections
- Water reduction features on medical equipment (washers, cart washers, sterilizers)
- Use of process chilled water with heat exchangers for cool down, temper, waste or condensate discharge from medical equipment (washers, sterilizers) and food service equipment in lieu of domestic water mixed into waste stream
- Laundry wash water recovery and reuse
- Clients using waterless hand sterilizers (alcohol based)
- Creation and implementation of water management plans
- Creation and implementation of management plan of green practices for custodial and cleaning processes
- Use of more disposable medical products in lieu of products that may typically be used, then washed and sanitized for use again
– As described in previous sections, well- planned, operated and maintained mechanical systems can help reduce the spread of airborne infections.
- Room Level HEPA Filtration – Affiliated Engineers, Inc. (AEI) developed an approach to patient room filtration that allows a standard Med/Surg room to be operated as a Patient Protective Environment (PPE) on an individual basis with no impact on the primary mechanical system. This provides the hospital with a high level of control and flexibility in scheduling rooms and serving patients. It also provides a means to boost filtration for a period of time after a patient is discharged to help sanitize the space before bringing in another patient. In the past, hospitals might wait 8-10 hours before assigning a room to another patient.
- Emergency Department Air Flow Rates – It is often not known until a patient arrives at a healthcare center whether or not they are infectious. Providing variable airflow rates in treatment rooms allows the airflow to be significantly increased beyond code minimums for a period of time to flush the room before another patient arrives.
The use of Computational Fluid Dynamics(CFD) modeling software is helping engineers better understand the path of air travel in spaces where patients, staff and public are more susceptible to contracting airborne infections such as surgery rooms, oncology treatment rooms and emergency waiting rooms. At the Lurie Children’s Hospital in downtown Chicago, CFD analysis informed the decision to implement a displacement air strategy in the Emergency Department waiting room. As illustrated in the image below air is introduced at the floor level at very low velocity. As the air warms it natural stratifies, thus reducing the amount of “mixing” prevalent in overhead, higher velocity distribution systems. This increases the quality of air breathed by room occupants, increases thermal comfort and reduces fan energy.
Patient-Centered Healing Environments
– A significant amount of research has occurred over the last ten years regarding the affects of lighting and personalized environmental controls in creating healthy/healing environments for patients and staff alike.
- Diurnal Lighting and Circadian Rhythm – It is widely known that exposure (duration, intensity and wavelength) to both daylight and electric lighting affect circadian rhythm and, thus, wellbeing. While the hospital setting is a 24-hour workplace, specific attention needs to be given to balancing the varying lighting needs of patients and staff during nighttime hours. Night shift workers need a comfortable lighting environment that is conducive to their needs, including increased lighting levels that enhance alertness and cue resetting of their biological clock. On the other hand, even small amounts of- and brief exposure to- electric lighting can disrupt a patient’s sleep pattern. Diurnal, zoned lighting controls can help balance the needs of both patients and clinical staff. Remote patient monitoring using in-room cameras is more widely used today to reduce the amount of disruption to patients during nighttime hours.
- Daylight and Patient Views – Access to daylight and exterior views contribute to a patient’s sense of well being and healing. Studies have shown that access to daylight can reduce the need for pain medication and reduce overall length of stay. With these benefits comes also the challenge of controlling glare and solar gains. Software tools can assist engineers in modeling the effects of daylight to provide the appropriate shade controls and glass transmittance.
- High Tech / High Touch – More and more, patients prefer greater control over their room environment (lighting, shades, temperature). Controls for each of these are now available in the patient’s pillow speaker/nurse call/television controller. Other amenities from the hospitality environment are finding their way into the patient room as well. LodgeNet, the leading hotel industry software provider of interactive TV services now has a line of products tailored specifically to the healthcare industry. The on-line features include room environment controls, room service dining, patient education, caregiver information and many more.