Texas Children's Hospital, Houston, Texas
Texas Children’s Hospital (TCH), located in the Houston Texas Medical Center, expanded from 2.7 million square feet in 2008 to the current 5 million square feet. That is almost a doubling in size in seven years. The respective utility budgets increased from $19 million to $26 million. The utility budgets are the total cost for chilled water, steam, electricity, and water. Note that the size of the institution increased by 85 percent but the utility budget only increased by 37 percent. Utility cost per square foot has been reduced from $7.04 to $5.20.
TCH is supplied with chilled water (CHW), 40 degrees to 42 degrees, and steam, 250 pounds, from a district system. Conservation and control of these sources must be accomplished at each individual building as the primary CHW temperature and steam pressures are constant.
The above utility cost reductions were accomplished by optimizing the operation of mechanical and electrical equipment. TCH spent no capital funds to accomplish the reductions. Everything was done using operating funds. Some examples of the energy cost measures (ECM) are:
- Accurate control of building chilled and hot water was instituted. Flows and temperatures of these resources are reset based upon space demand.
- Room ventilation schedules for over 4,000 individual rooms were revised to ensure compliance with standards and to increase comfort.
- Occupied and unoccupied schedules were implemented where possible.
- Building automation system (BAS) control sensors were calibrated or replaced to increase control accuracy.
TCH accomplished these, and other ECMs, by hard work. An even harder task was how to monitor these complex systems and make sure that the new operational settings were not compromised. Two tactics were implemented to monitor the operations:
- A daily, 24-hour manual override scorecard was developed and implemented for the BAS.
- A daily measurement and verification (M&V) process was developed and implemented to monitor the consumption of utilities.
Manual override report – (Attachment #1): This report is automatically generated and distributed by the BAS. The BAS is large and has almost 65,000 individual control and data points. The manual override report captures all actions such as:
- Placing a control point in manual.
- Changing an individual controller set point.
- Overriding a control system.
Each occurrence listed in the daily report identifies the individual BAS point what was changed, the date and time of the occurrence, the name of the individual that made the change, and the state of the change.
When the override report was started it was routinely over two pages of changes. Currently the report is one page and many weekend reports contain only six to ten changes. The daily report is sent to operations leadership for analysis and any required action. This simple report has helped reduce the number of bypassed systems. It also serves as a teaching tool for operations management with respect to coaching field technicians when it is appropriate to change a point and when some other action should be taken.
Daily M&V scorecard – (Attachment #2): A separate score card is made every day for individual buildings. Each building’s score card shows how much chilled water, electricity and steam a building used the previous day and what the building should have used. The International Performance Measurement and Verification Protocol (IVMPV) is the basis of the process. The M&V process is based upon an individual energy model for each building. The energy models are based on historical data. A minimum of one year's worth of data is required to develop a building’s energy model. The following data is required to develop the model:
- Daily chilled water consumption
- Cost for chilled water
- Daily electricity consumption
- Cost for electricity
- Daily steam consumption
- Cost for steam
- Average daily dry bulb outside temperature, and
- Average daily dew point outside temperature.
The data is used for developing a multi-variable regression analysis equation for each building. This equation is the energy model, and basis for the report, for a building. Each day weather data from NOAA is used, along with the day’s energy data, is used to calculate each report. The report uses graphs and tables to display a building’s performance. It just takes a quick glance to determine is an energy source is being over used. Examples of successes using the M&V scorecard:
- It helped identify a leaking steam vent in a research building which caused excessive consumption of steam. The vent was replaced.
- It helped identify excessive primary chilled water consumption in the TCH Pavilion for Women. The problem was identified as a main bypass valve that had been manually opened.
The TCH campus energy use intensity (EUI) in has been reduced from a high of 333.9kBtu/SF to a current 233.5kBtu/SF, which generated total energy cost savings of $10.3 million since 2008. Annual savings are now exceeding $2.5 million. This level of savings would not have been possible without the manual override reports and the daily M&V scorecards.