Kapileshwari and Robison- Gulf Coast Green 2010
•Als PPT, PDF herunterladen•
0 gefällt mir•352 views
Big Dreams, Tight Budgets: UH Retro-Commissioning to Reduce Carbon Footprint Authors: Sameer Kapileshwari, University of Houston Facilities and Cole Robison, Controls Unlimited
![Big Dreams Tight Budgets: UH retro-commissioning to reduce Carbon footprint ,[object Object],[object Object],[object Object],[object Object],[object Object]](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Empfohlen
Empfohlen
Weitere ähnliche Inhalte
Was ist angesagt?
Was ist angesagt? (20)
Andere mochten auch
Ähnlich wie Kapileshwari and Robison- Gulf Coast Green 2010
Ähnlich wie Kapileshwari and Robison- Gulf Coast Green 2010 (20)
Mehr von Hayley Pallister
Mehr von Hayley Pallister (20)
Kürzlich hochgeladen
Kürzlich hochgeladen (20)
Kapileshwari and Robison- Gulf Coast Green 2010
- 1. Big Dreams Tight Budgets: UH retro-commissioning to reduce Carbon footprint Presented at Gulf Coast Green - 2010 April 15, 2010 University of Houston Houston, TX
- 8. Buildings Implemented on Campus
- 13. UH RCX Project - 2009
- 15. Energy Efficiency & Sustainability Milestones
- 21. Evaluation Period / Temperature
- 23. Evaluation Period / Chilled Water
- 25. Evaluation Period / Electrical
- 26. Evaluation Period / Trending Review
- 27. Trended Energy Data Sample
Hinweis der Redaktion
- US DOE reports that buildings account for 72% of US electricity consumption and 40% of US CO2 emissions. More than half of the commercial buildings built before 1980 (when energy codes largely did not exist) have yet to undergo energy related retrofit, representing enormous opportunity to reduce building energy consumption.
- Definition Existing-building commissioning, also known as retro-commissioning, is an event in the life of a building that applies a systematic investigation process for improving or optimizing a building’s operation and maintenance. It may or may not emphasize bringing the building back to its original intended design. The retro-commissioning process most often focuses on dynamic energy-using systems with the goal of reducing energy waste, obtaining energy cost savings, and identifying and fixing existing problems .
- Cameron Cameron is a two story building that is split into two halves serving separate schools. The west half is a single story and the east half has two stories. There are two main air handlers which are served by separate outdoor air handlers. The smaller of the two air handler serves 9 mixing boxes in the west half while the larger air handler serves 22 mixing boxes on two floors of the east half. This building utilizes a dual duct scheme for conditioning purposes. The air handlers are not equipped chilled water valves and instead control discharge temperature through reheat. This building is unique in that it is the only building of the five to have its own chillers and boilers. There are two, identical, 70 ton, air-cooled chillers each served by a 5HP pump. A single boiler provides hot water to the air handlers for reheat. Technology Technology is a single story building that is served with hot and chilled water by the central plant. There is a single VFD-controlled chilled water pump and a constant speed hot water pump. AHU #3 is a dual duct unit serving 10 mixing boxes in the east side of the center of the building. The remaining three air handlers are VAV units with variable frequency drives and chilled water coils only; they supply a total of 18 VAV boxes equipped with hot water reheat. Engineering By far the largest building in this study, Engineering is comprised of 3 floors and a basement. The original AHUs include two rooftop outdoor air units, two AHUs on each of the 3 floors, and seven AHUs in the basement. The six main AHUs, two per floor, are all three duct systems. There is the main cold duct, and then a central zone hot duct, and a perimeter zone hot duct. The AHUs serve the zones with mixing boxes. The basement air handlers are mixed between single and multi-zone. AHU B1, B2, B5, and B7 are all dual duct design with mixing boxes at the zones. AHU B3 and B4 are single zone air handlers. AHU B6 is the only AHU with a single duct that serves VAVs with hot water reheat. The two rooftop units, R1 and R2, are the original outdoor air units that supply all of the air handlers within the building. Each is equipped with a VFD which is controlled by a static pressure setpoint. When the University recently installed additional exhaust fans to serve the laboratory space, seven single zone, constant speed, OAHUs were added at the same time; three on the third floor that serve the atrium and four in the basement. Combined, there is 81,000 cfm of outdoor air continuously supplied from nine OAHUs for ventilation and make-up air for the fume hoods. Hot and chilled water for the handlers is supplied from two chilled water pumps and one hot water pump located in the basement. The roof-mounted exhaust fans are organized into multiple fan systems that gang together multiple exhaust ducts. The system provides redundancy should one of the fans fail. There is one 3-fan system that only uses two fans at a time and four 2-fan systems that run one fan at a time. The exhaust fans are run 24 hours a day and are constant volume. Communications The Communications and Wortham buildings share chilled and hot water pumps . There is a single 7.5 hp hot water pump and two parallel 40 hp chilled water pumps. There are two main air handlers; AHU 10 is on the second floor and AHU 9 is on the first. These are variable volume with VFD fan motors. AHU 10 draws untreated outdoor air through a vent on the roof while AHU 9 receives pretreated outdoor air from an outdoor air unit, OAHU 11, located in the same mechanical room as AHU 10. There are two smaller AHUs, 12 and 13, that are single zone, constant volume with no outdoor air intake. There are seven hot water fan coil units that provide additional heating to the perimeter zones when it is needed. The air handlers operate from 5am to 11pm daily. Wortham Wortham is composed mainly of a 566 seat auditorium that is served by two single zone, variable volume air handlers. AHU 7 serves the stage area and AHU 8 serves the seating area. There is a large scenery shop located behind the stage that is served by the single zone, variable volume AHU 1. The classrooms and workshops in the rest of the building are served by multi-zone variable volume AHUs 2-5 with the exception of the single zone, constant volume AHU 4 which serves a large classroom. There is no AHU6. The air handlers operate from 5am to 11pm daily.
- 2.1 Change Preheat Setpoint for Cameron OAHU 1 The hot water valve for this outdoor air handler was set to heat the incoming air to 90°F no matter what the outdoor temperature. University staff lowered this setting to 55°F. A picture of the pneumatic control box is seen in Figure 1. 2.2 Communications OAHU Schedule Because this building was already on a DDC system with time of day scheduling in place, university staff only had to change the schedule of the units associated with ventilation to 8am-5pm. 2.3 Wortham OAHU Schedule This measure is similar to the previous one. The schedule for units associated with ventilation was changed to 8am-5pm. 2.4 Communications Exterior Lights For this measure it was determined that the DDC point was never correctly mapped to control the exterior lights. The most cost effective way to implement this measure was to put the circuits on a mechanical time clock.
- Engineering Lighting This measure was implemented through the use of a mechanical time clock. This would allow the unnecessary lights to be turned off at night. Without the use of photocells, no peak savings will be achieved, but annual savings will be present. Add Ceiling Fans to Wortham It has a 15 foot diameter and uses a 2 HP motor. This “low velocity, high volume” fan will enable the fan speed on the 7.5 HP motor to be reduced to only what is required to heat and cool the space. Prior to these fans being installed, the fan was run at 100% speed all day long. Reduce Engineering Outdoor Air The bypass dampers on the exhaust fans systems were repaired or retro-fitted with dampers and actuators so they can modulate to maintain a static pressure set point. New airflow measuring stations were installed to measure both the bypass airflow through the new dampers as well as the outdoor airflow into the building through the rooftop units R1 and R2. The designed building pressure will be maintained by only reducing the incoming outdoor airflow by an amount equal to the airflow through the bypass dampers. Figure 12 shows one of the existing bypass dampers that were retrofitted. Figure 13 shows the trending of the VFD speed for OAHU R1 and R2. The building ventilation system is quite complicated and will take a while to fine tune. Notice that one of the units is running much faster than the other. This is most likely due to the position of the largest of the exhaust fans is on that side of the building which would require more ventilation air. It is a positive sign that the other OAHU is now running in the 20 to 40% speed range which yields significant savings.
- Demand Controlled Ventilation for Cameron New actuators and dampers were installed on the outdoor air handlers for Cameron. Outdoor airflow into the building will be controlled in three stages based upon CO2 measurements and setpoints: outdoor air damper closed, damper open fan off, and damper open fan on. As the CO2 measurements begin to rise, the damper will open to allow the main air handler to pull a small amount of fresh air through the open damper. If the CO2 levels continue to rise, the fan for the outdoor air handler will turn on to increase airflow. The hot and chilled water valves on the outdoor unit will continue to condition the air so long as the damper is open. Please note that the University of Houston decided to replace the chilled water coil on OAHU 1 during the process of implementing this measure. Figure 15 shows the new outdoor air damper for OAHU 2. Figure 16 and Figure 17 show a week long trend of the CO2 concentration and the damper position. Notice that the damper closes outside of the normal building occupancy schedule and is at 10% a majority of the time. If the CO2 concentration rose above the setpoint the damper opens to 100% as shown in Figure 16. Also note in Figure 16 that the CO2 level is getting much lower than the minimum expected, 350 ppm. This sensor has since been recalibrated. Reset VFDs to Automatic A contract for a set number of hours was given to solve as many of the VAV issues as possible. The automatic control for all of the listed air handlers has been reinstated which allows the VFDs to vary the speed of the fan motor with the building load. The speed of the VFDs has been trended to show the changes and can be seen in Figure 19. Technology DDC A new DDC system was installed for this building to replace the antiquated pneumatic system. Points were added to control and monitor the fans motors for all air handlers and exhaust fans as well as the discharge air temperature of the air handler units. This new system also allowed the university to schedule the units to turn off at night when the building is unoccupied. Figure 21 shows the new controls cabinet for the building. The box has the capacity to add addition points onto it, such as VAV boxes or room temperature sensors, in the future. Figure 22 through Figure 27 show the runtime logs for AHUs 1, 2, 3, and 4 as well as the hot and chilled water pumps. These show the equipment turning off and on at the specified times. The first few times may be skewed as the schedules were just being set up and tested. Cameron DDC Similar to the previous measure, a new DDC system was installed for this building to replace the antiquated pneumatic system. Points were added to control and monitor the discharge air temperature, status of the fans motors for all air handlers and exhaust fans, as well as status and control for the pumps and chillers. This new system also allowed the university to schedule the units to turn off at night when the building is unoccupied. The status of these fans was logged to show when the fans turned off and on. Figure 28 shows the supply temperature from OAHU 2. The occupied mode can be seen in the tight oscillations around the temperature setpoint of 53°F. During the unoccupied mode, the temperature trends more smoothly and moves toward the outdoor temperature. It has been suggested to tweak the PID loop for the chilled water valve to correct these rapid movements. Figure 30 and Figure 31 show the runtime logs for AHUs 1 and 2. These show the air handlers turning off and on at the specified times. The first few times may be skewed as the schedules were just being set up and tested. A picture of one of the new CO2 sensors is shown below.
- 150K tons of CO2 (46% - Buildings, 51%-Commute)