Executive SummaryTerminal boxes usually serve a single building zone, controlling the air-flow rate to the zone and reheating the air when it is too cool. Each terminal box has a minimum air-flow rate that ensures the ventilation requirements of the occupants of the zone served are met. This minimum air-flow rate is maintained at a constant value based on the design occupancy of the zone, which often corresponds to the maximum occupancy, because measurements of actual occupancy are not currently used to adjust the flow rate. Therefore, the minimum flow rate must meet the ventilation needs of the fully occupied zone. The total flow rate may be higher than the minimum to provide adequate cooling or heating, but the minimum for ventilation should always be met.In practice, control system integrators and installers often set the cooling minimum air-flow rate for ventilation to between 30% and 50% of the maximum air-flow rate of the terminal box. Building occupancy, however, varies dynamically. Conference rooms, cafeterias, auditoriums, and other assembly spaces are often unoccupied for significant periods of time. Office occupancy varies during the course of a work day, from day to day, and over the longer term because of attendance of meetings elsewhere, business travel, changing room functions, and variations in staffing. The resulting overventilation, during times when the space has less than maximum occupancy or is unoccupied, wastes significant fan energy and causes discomfort for occupants in some spaces (e.g., conference rooms) from overcooling or overheating, especially in interior zones that do not have reheat in the terminal boxes.Common occupancy sensors, which measure whether occupants are present or not, are commonly used for lighting control in conference rooms and other spaces with variable occupancy. They could be used to enable a terminal box to be switched to an occupied standby mode in which the air-flow rate is set to zero when no occupants are in the zone the box serves. If advanced occupancy sensors, which count the actual number of occupants in a room, were used to control terminal boxes, the minimum air-flow rate set point for the terminal box could be reset dynamically based on the actual occupancy sensed. This study evaluates the savings potential from use of occupancy-based control (OBC) of terminal boxes for large office buildings with variable-air-volume (VAV) heating, ventilating and air-conditioning (HVAC) systems using both common occupancy sensors and advanced occupancy sensors.Large office buildings were selected for this study because they represent the subsector of commercial buildings with the greatest use of VAV HVAC systems in the U.S. They contribute 4.4 billion ft 2 of floor space and represent 6.1% of the total commercial floor space.Energy savings are determined from estimates of annual energy consumption obtained from simulations of representative large office buildings with and without OBC of terminal boxes and lighting for all 15 U.S. climate zones. The building without ...
This multi-year research study was initiated to find solutions to improve packaged heating and cooling equipment operating efficiency in the field. Pacific Northwest National Laboratory (PNNL), with funding from the U.S. Department of Energy's (DOE's) Building Technologies Office (BTO) and Bonneville Power Administration (BPA) conducted this research, development and demonstration (RD&D) study.Packaged heating and cooling equipment with constant speed supply fans is designed to provide ventilation at the design rate at all times when the fan is operating and when the building is occupied as required by building code. Although there are a number of hours during the day when a building may not be fully occupied or the need for ventilation is lower than designed, the ventilation rate cannot be adjusted easily with a constant speed fan. Therefore, modulating the supply fan in conjunction with demand controlled ventilation (DCV) will not only reduce the heating/cooling energy but also reduce the fan energy.The objective of this multi-year RD&D project was to determine the magnitude of energy savings achievable by retrofitting existing packaged rooftop air units (RTUs) with advanced control strategies not ordinarily used for RTUs. First, in FY11, through detailed simulation analysis, it was shown that significant energy (between 24% and 35%) and cost savings (38%) from fan, cooling and heating energy consumption could be realized when RTUs with gas furnaces are retrofitted with advanced control packages (combining multi-speed fan control, integrated economizer controls and DCV). The simulation analysis also showed significant savings for heat pumps (between 20% and 60%). The simulation analysis was followed by an extensive field test of a retrofittable advanced RTU controller.In FY12, a total of 66 RTUs on 8 different buildings were retrofitted with a commercially available advanced controller for improving RTU operational efficiency. Of the 66 RTUs, 17 were packaged heat pumps and the rest were packaged air conditioners with gas heat. The eight buildings cover four building types, including mercantile (both retail and shopping malls), office, food sales, and healthcare. These buildings are located in four different climate zones, including warm and coastal climate, mixed and humid climate, mixed and marine climate, and cool and moist climate. One-minute interval data was collected from these 66 units over a 12-month period. During the 12 months of monitoring period, the controls on the RTUs were alternated between standard (pre-retrofit mode) and advanced control modes on a daily basis. The measured actual savings, the normalized annual energy savings, and the savings uncertainties were calculated using the methods described in the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) Guideline 14. Major findings from this work are highlighted below: The advanced controller reduced the normalized annual RTU energy consumption between 22% and 90%, with an average of 57% for all RT...
In FY13, Pacific Northwest National Laboratory (PNNL), with funding from the Department of Energy's (DOE's) Building Technologies Office (BTO), designed, prototyped and tested a transactional network platform to support energy, operational and financial transactions between any networked entities (equipment, organizations, buildings, grid, etc.). Initially, in FY13, the concept demonstrated transactions between packaged rooftop air conditioning and heat pump units (RTUs) and the electric grid using applications or "agents" that reside on the platform, on the equipment, on a local building controller or in the Cloud. The transactional network project is a multi-lab effort with Oakridge National Laboratory (ORNL) and Lawrence Berkeley National Laboratory (LBNL) also contributing to the effort. PNNL coordinated the project and also was responsible for the development of the transactional network (TN) platform and three different applications associated with RTUs. This document describes two applications or "agents" in detail, and also summarizes the platform. The TN platform details are described in another companion document.
The Department of Energy's (DOE's) Building Technologies Office (BTO) is supporting the development of the concept of "transactional network" that supports energy, operational, and financial transactions between building systems (e.g., rooftop units --RTUs), between building systems and the electric power grid using applications, or 'agents' that reside either on the equipment, on local building controllers or in the Cloud.As part of this Transactional Network initiative, BTO has funded Pacific Northwest National Laboratory to develop an open source, open architecture platform that enables a variety of site/equipment specific applications to transact in a cost effective and scalable way. The goal of this initiative is to lower the cost of entry for both existing and/or new service providers because the data transport or information exchange typically required for operational and energy-related products and services will be ubiquitous and interoperable.The transactional network platform consists of VOLTTRON™ agent execution software, a number of agents that perform a specific function (fault detection, demand response, weather service, logging service, etc.). The platform is intended to support energy, operational, and financial transactions between networked entities (equipment, organizations, buildings, grid, etc.). This document is a user guide for the deployment of the transactional network platform and agent/application development within VOLTTRON. The intent of this user guide is to provide a description of the functionality of the transactional network platform. This document describes how to deploy the platform, including installation, use, guidance, and limitations. It also describes how additional features can be added to enhance its current functionality.
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