Existing Mechanical Conditions

Transcription

1 Figure 2 Existing Mechanical Conditions Design Parameters During the entire project, various general and discipline specific parameters affected the design approach. These design parameters include governmental, program, cost, site, and HVAC or system type which includes central plant. Federal, State, and Local governments regulate and mandate standards for national energy consumption and conservation, general state building codes and standards, and Elementary and Secondary education standards. At the national level President George W. Bush stated, America must have an energy policy that plans for the future, but meets the needs of today and revised America s National Energy Policy. In 1999, America consumed quadrillion btu s of energy. At the state level, the state of Ohio produces and publishes the Ohio Building Code that establishes construction standards for all construction within the state. This code reflects the national building codes such as the BOCA Building code or the International Building Code, but Ohio modifies these codes for Ohio needs. In addition, the Ohio Schools Facilities Commission, establishes comprehensive program standards for school districts that 05APR

2 renovate or construct educational facilities. General program requirements include general classroom, laboratory classroom, administration, library/media center, full auditorium and stage, kitchen and dining, general trades or shop use, music practice and education, sports gymnasium and supporting facilities. Many design parameters and constraints affect the HVAC system concept, type and configuration, and equipment type. Foremost, the Ohio School Facilities Commission establishes minimum requirements and publishes these requirements in a design guideline. Chapters six and eight discuss program, including environmental features, and HVAC respectively. Appendix A includes a printed copy of portions of chapter eight. The reader may refer to this appendix for more detailed information. Regarding program HVAC support, the design guide briefly discusses ventilation and requires higher than normal ventilation requirements. The design guideline also requires compliance with ASHRAE 90.1 for minimum energy performance criteria. The design guideline prefers four HVAC system types and only permits alternatives if the Design Professional completes an evaluation detailing the system annual operating cost, which includes maintenance cost and installation costs, and submits the report for approval to the Ohio School Facilities Commission. These system types include Central Plant Variable Air Volume System with Reheat Terminals, Central Plant Variable Air Volume System with Fan Powered Reheat Terminals, Water Source Heat Pump, and Central Plant Dual-Duct Constant Air Volume Systems with Dual Duct Constant Volume Terminals. For the New Independence High School/Shared Use Facility, the HVAC Design Professional chose the Central Plant Variable Air Volume System with Reheat Terminals. The facility receives electrical energy from The Cleveland Electric Illuminating Company, a subsidiary of First Energy, and natural gas, for thermal energy, from East Ohio Gas Company, a subsidiary of Dominion. Cleveland pays one of the highest utility rates in the country. Appendix B includes copies of utility rate information. All Owners desire maximum product for minimum cost. However, the New Independence High School Owners understood the importance of a modern facility to meet new education demands and challenges and accommodated the slightly higher than normal cost for this facility. The HVAC construction installation cost for this project is approximately million of a total project construction cost of approximately 33 million. This ratio is approximately 13.3% and results in a $21.73 HVAC cost per square foot. This cost only involves the HVAC and does not include the other traditional mechanical plumbing and fire suppression systems costs. RS Means indicates that the high HVAC range for this type of building is $3,987,00. Therefore the HVAC costs appear slightly higher than the normal range. Annual operating costs are currently undetermined since the facility is in construction and detailed energy/cost modeling was not conducted by the HVAC Design Professional. Existing Systems Overview and Comments Generally, the New Independence High School/Shared Use Facility uses variable temperature conditioned, constant or variable air to moderate heating and cooling loads, and provide ventilation, within the facility. Sixteen air-handlers, two packaged rooftop units, three make-up-air units, and two air-recirculation units support the nineteen primary zones of the 114,030 square foot plus building. Two rotary screw, air cooled chillers provide cooling and a battery of eleven modulating output, hot water boilers provide the heating or cooling needs. In addition, a battery of 05APR

3 constant and variable volume pumps distribute the 40% glycol, chilled or hot water to the system coils. Only one packaged rooftop unit utilizes DX cooling and neglects the use of chilled water. As mentioned earlier, Specifications section Facility Management System includes the detailed sequence of operations for all the HVAC equipment. This 130 page section may be made available at the instructor s request. Refer to Appendix C for HVAC system zoning plans. COOLING PLANT The central cooling plant consists of: Two air-cooled, rotary screw chillers, and pump distribution. The general control logic for these systems involves interlocking with the Facility Management System (FMS) system. The chillers have dedicated controllers that maintain proper operation. During unoccupied mode (managed by time clock) or night set back, the controller cycles the chillers to maintain chilled water temperature setpoints. During occupied mode (managed by time clock), the controller stages the chillers to maintain chilled water temperature setpoints. The control sequence includes pump current status as well as internal chiller alarms communication to the FMS. HEATING PLANT The Heating plant consists of: eleven natural gas fired, separated combustion air, multi-staged, hot water boilers form two batteries (one for the school and one for the community facility), and pump distribution. The general control logic for these systems involves interlocking with the FMS system. The boilers have dedicated controllers that maintain proper operation. During unoccupied mode (managed by time clock) or night set back, the controller cycles the boilers to maintain hot water temperature setpoints. During occupied mode (managed by time clock), the controller stages the boilers to maintain hot water temperature setpoints. The control sequence includes pump current status as well as internal boiler alarms communication to FMS. The following diagrams illustrate the current cooling, heating, and main electrical switchgear system schematics. 05APR

4 Cooling Plant Schematic 05APR

5 Heating Plant Schematic 05APR

6 Electrical Main Switchgear Schematic 05APR