Heating, ventilation & air conditioning (HVAC)
HVAC control systems are seldom adjusted to optimize energy efficiency while providing appropriate temperature control and ventilation. Older control systems are simply incapable of producing optimum HVAC operation. Few control systems are continually “commissioned” so they tend to drift out of adjustment. To one extent or another, few hospitals have well controlled HVAC systems.
A poorly controlled HVAC system can have substantial impacts on the costs of facility operation and the Environment of Care. By design, these control systems are self-adjusting to maintain comfort so the first warning of serious problems occurs when work orders start coming in from the occupants. There are at least 3 stages of decline:
- The cost of operation is higher than it could be with optimal control and well maintained equipment. Efficiency losses can exceed 25 percent. Most facilities are in this category.
- If things get worse, more equipment is needed to maintain the environment of care and redundant equipment may be turned ON to compensate for system inadequacies. At this point, the facility no longer has adequate redundancy in the event of equipment failure.
- The HVAC system is unable to adequately heat, cool and/or ventilate sections of the facility. There may be enough equipment capacity but poor control/maintenance compromises the environment of care.
The hospital HVAC system typically consumes 30 to 35 percent of the total electrical energy and over 50 percent of the heating energy. Low/No cost improvements might reduce HVAC energy consumption up to 25 percent. Capital improvements in the form of variable speed drives, new chillers, cooling towers, boilers and piping modifications coupled with optimal control can save another 15 to 35 percent.
Facility electric bills could be reduced by 7 to 21 precent and heating bills could be reduced by 15 to 30 percent.
Bundling Low/No cost improvements with capital improvements may reduce the package payback to between 3 and 5 years. This is a complex process and the pay back can exceed 10 years in some cases.
Implementing a comprehensive HVAC control retrofit
This can be the most complex project a hospital may undertake. Selecting a very talented consultant/coach can pay for itself many times over. Consider purchasing these services directly rather than coupling their fees to the cost of the retrofit.
Why retrofit/replace HVAC equipment?
Hospitals seldom replace a working chiller or boiler for the sake of energy savings. This seldom occurs unless a strategic energy management plan and/or energy services company (ESCO) contract has been implemented. More commonly, new big HVAC equipment is only purchased due to failure or as part of new construction.
If there are new chiller or large HVAC repair bills in your near future you might save hundreds of thousands of dollars in Net Present Value by having a qualified person use the chiller tool (which can also be used to do NPV comparisons for other types of equipment).
Yes, there are many ways of justifying retrofit or replacement of working equipment.
Heat recovery is seldom used to maximum advantage. Most hospitals constantly spend money discarding more heat than the hospital ever needs. Modern large heat recovery chillers make it possible to never purchase fossil fuel heat except for sterilization. The heat recovery chillers cost more than conventional chillers but they make it possible to avoid the cost of boilers as the primary source of heat. Yes redundant fossil fuel boilers must still be purchased but the avoided redundant primary boiler costs more than compensate for the incremental heat recovery chiller costs. Heat recovery chillers can be cost effectively used in new construction and retrofit applications.
Hospital HVAC systems typically consumes 30 to 35 percent of the total electrical energy and over 50 percent of the heating energy. Equipment improvements in the form of variable speed drives, new chillers, cooling towers, boilers, piping, pumping and ventilation modifications coupled with optimal control can save 40 to 60 percent.
Facility electric bills can be reduced by 20 percent and heating bills can be reduced by 30 percent.
Bundling low/no cost improvements with capital improvements may reduce the package payback to 4± years versus over 10 years in some cases when bundling is not used.
Implementing a comprehensive HVAC retrofit or purchasing new equipment
Spending 20 percent more than low bid on a chiller, boiler, air handling unit, etc. can pay for itself through lower system costs and through the net present value. Selecting a very talented consultant/coach can pay for itself many times over.
Lighting efficiency can often be improved 25 to 60 percent and that will significantly reduce cooling requirements. If lighting is retrofitted prior to the purchase of new HVAC equipment, then the new HVAC size and costs can be substantially reduced.
Sample documents and resources from conservation catalysts
- Chiller Estimator
Simple Calculator – Chiller total cost estimator
- Electric Motors
Discussion of electric motors used in HVAC applications with specifications.
- HVAC Control Valve
Explanation of HVAC control valves and their use in design.
- Pump Impellers
Engineering overview of pump impellers and their use in HVAC applications
- Reduce Opposition to Flow
Symptoms and common causes of air and water flow problems in HVAC design.
- Sample HVAC Controls
Design instructions for mechanical consultant and architect on HVAC control systems.
- Sample HVAC Design Guide
HVAC design guide for large owner maintained multi-wing facility.
- Sample Variable Frequency Drive Appendix
- HVAC design recommendations of variable frequency drive’s and how they apply to fans, pumps, chillers, vacuum pumps and air compressors.
- Sample Ventilation Ductwork Concepts
Document that explains the symptoms of common ductwork problems and leaks, also explain the value of minimizing ductwork problems.
- Varialble frequency drives (VFD) design guide
Purchasing and applying variable frequency drives (VFD) in HVAC applications