Heating Ventilating and Air Conditioning HVAC Controls Codes and Standards Enhancement CASE Study November 28 2000 Pacific Gas and Electric Company Patrick Eilert Pacific Gas and Electric Co P O Box 770000 H28E San Francisco CA 94177 Phone 530 757 5261 E mail ple2 pge com This report was prepared by Pacific Gas and Electric Company and funded by California utility customers under the auspices of the California Public Utilities Commission Neither PG E nor any of its employees and agents 1 makes any written or oral warranty expressed or implied regarding this report including but not limited to those concerning merchantability or fitness for a particular purpose 2 assumes any legal liability or responsibility for the accuracy completeness or usefulness of any information apparatus product process method or policy contained herein or 3 represents that use of the report would not infringe any privately owned rights including but not limited to patents trademarks or copyrights Copyright 2000 Pacific Gas and Electric Company All rights reserved Reproduction or distribution of the whole or any part of the contents of this document without the express written permission of PG E is prohibited Neither PG E nor any of its employees makes any warranty express or implied or assumes any legal liability of responsibility for the accuracy completeness or usefulness of any data information method policy product or process disclosed in this document or represents that its use will not infringe any privatelyowned rights including but not limited to patents trademarks or copyrights CASE HVAC CONTROLS FINAL DOC This page intentionally left blank COPYRIGHT 2000 PACIFIC GAS AND ELECTRIC COMPANY Table of Contents ACKNOWLEDGMENTS II INTRODUCTION 1 TECHNOLOGY DESCRIPTION 1 CURRENT PRACTICE 1 ECONOMIZERS 1 FAN CONTROLS 2 DIAGNOSTIC SYSTEMS 3 MARKET CHARACTERISTICS 3 EQUIPMENT RELIABILITY 5 ECONOMICS 5 COSTS 5 BENEFITS 5 AVAILABILITY 7 STATEWIDE ANALYSIS 8 KEY STAKEHOLDERS 9 IMPLEMENTATION STRATEGIES AND RECOMMENDATIONS 9 APPLIANCE EFFICIENCY REGULATIONS 9 ENERGY EFFICIENCY STANDARDS FOR BUILDINGS 9 VOLUNTARY STANDARDS 10 FUTURE RESEARCH 10 BIBLIOGRAPHY 11 CASE STUDY PAGE I COPYRIGHT 2000 PACIFIC GAS AND ELECTRIC COMPANY Acknowledgments The New Buildings Institute developed this Codes and Standards Enhancement Study for the Pacific Gas and Electric Company under Contract 4600010614 part of PG E s Codes and Standards Program for 1999 Project managers for PG E included Jennifer Barnes Patrick Eilert Gary Fernstrom and Marshall Hunt Jeffrey A Johnson Senior Program Director of the New Buildings Institute managed this project Subcontractors on this project were Eley Associates Charles Eley Architectural Energy Corporation Pete Jacobs Dave Roberts Kosol Kiatreugwattana Dan Bertini Don Felts Energy Consulting Don Felts The following individuals reviewed and advised the project Cathy Higgins New Buildings Institute Bill Pennington Michael Martin and Jonathan Leber California Energy Commission Produced by New Buildings Institute Inc PO Box 653 White Salmon WA 98672 E mail info newbuildings org Web www newbuildings org PAGE II HVAC CONTROLS COPYRIGHT 2000 PACIFIC GAS AND ELECTRIC COMPANY Introduction This Codes and Standards Enhancement CASE Study provides information to support updating HVAC Controls requirements in California s Energy Efficiency Standards for Nonresidential Buildings Standards In addition the study looked at possible changes to the Title 20 Appliance Efficiency Regulations Regulations This CASE study examines the following issues relative to HVAC controls on unitary equipment Economizer controls Diagnostic systems Thermostats and fan controls This CASE study for HVAC controls discusses the technology current practice economics key stakeholders and implementation options and recommendations for inclusion into codes Technology Description HVAC controls on unitary equipment include internal control systems supplied with the equipment by the manufacturer and external controls that control the delivery of heating cooling and ventilation services according to occupant requirements Internal control systems for unitary equipment include outdoor air damper economizer controls refrigerant flow controls heat pump refrigerant reversing controls heat pump compressor and strip heat controls compressor staging controls and condenser fan staging controls CASE STUDY This study focuses on economizer controls including dampers linkage actuators temperature sensors and electronic and or electromechanical components required to determine damper position External controls include manufacturersupplied or third party thermostats that control delivery of heating cooling and ventilation services The thermostats may also include a time clock for temperature setback during unoccupied periods and fan operation controls Depending on the local thermostat setting the fans may operate continuously or operate only when the unit is supplying heating or cooling cycle on call Diagnostic capability refers to selfmonitoring systems installed to detect unit operational faults that may or may not influence comfort but may have a significant influence on energy consumption An example of this is a diagnostic system designed to detect problems in economizer operation Current Practice Economizers The Standards exempt rooftop units under 75 000 Btu hr nominal cooling capacity 6 25 ton from economizers Thus most units 6 tons and smaller do not utilize economizers Conversely most units larger than 6 tons have outdoor air economizers The Standards also require an integrated economizer which is capable of providing partial cooling even when mechanical cooling is required to meet the remaining cooling load Effective operation of an integrated economizer requires a compressor system that provides stable operation at partial cooling output Units larger than 6 tons generally use multistage compressors to provide at least two discrete levels of cooling output PAGE 1 COPYRIGHT 2000 PACIFIC GAS AND ELECTRIC COMPANY Control strategies used with integrated systems include Fixed temperature The economizer shuts off when the outdoor temperature exceeds a fixed set point usually 75 F Differential temperature The economizer shuts off when the outdoor temperature exceeds the return air temperature Fixed enthalpy The economizer shuts off when the outdoor enthalpy exceeds a fixed value Differential enthalpy The economizer shuts off when the outdoor air
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