Recent cedr_cbe_cit items

Energy Performance of ASHRAE Guideline 36 Hydronic Sequences in Existing HVAC Systems Enabled by Portable, Semantic Interoperability Tools

Fri, 3 Apr 2026 00:00:00 +0000

ASHRAE Guideline 36 defines standardized high-performance control sequences for heating, ventilation, and air conditioning (HVAC) systems, yet limited field evidence exists on its plant-level applications. In this project, the team implemented Guideline 36 supply water temperature reset sequences for two hot water plants and a chilled water plant using a layered architecture of supervisory control, Building Automation and Control Networks (BACnet) communication, Control Description Language (CDL) based programming developed by ASHRAE Standard 231p, and Brick ontology to ensure scalability and interoperability. Measurement and verification (M&V) with weather normalization showed savings of 3.28 kBTU/ft²-year (10.38 kWh/m2-year)(7.5%) and 10.15 kBTU/ft²-year(32 kWh/m2-year) (11.5%) for the hot water plants, and 6.61 kWh/m2 (2,097 BTU/ft2) (14.6%) for the chilled water plant, translating to cost reductions of $0.095/ft2-year ($1.02/m2-year), $0.17/ft2-year ($1.82/m2-year), and...

ASHRAE Guideline 36 Open Source Supervisory Control Technology Development and Demonstration

Mon, 16 Mar 2026 00:00:00 +0000

ASHRAE Guideline 36 (G36) establishes industry best practice standardized sequence of operations for heating, ventilation, and air conditioning systems, including airside systems, chilled water plants, and hot water plants. Previous research studies have implemented airside system sequence of operations to show up to 35 percent energy savings over existing control strategies. This project demonstrated a scalable approach to implementing G36 sequence of operations for chilled water and hot water plants in existing buildings.

The team used the supervisory control layer to coordinate G36 logic with existing building automation systems without requiring major infrastructure changes. Using Control Description Language, the team implemented control logic to promote transparency, modularity, and alignment with G36 specifications, and applied Brick ontology to tag heating, ventilation, and air conditioning system data points.

To evaluate performance, the research team conducted...

Commercial Building HVAC Functional Performance Test Automation Using Brick Metadata Schema

Mon, 23 Jun 2025 00:00:00 +0000

Heating, ventilation, and air-conditioning (HVAC) system functional performance test is a critical commissioning step in ensuring the design, installation, and operation of the building's mechanical system is verified against its intent. HVAC systems in commercial buildings are complex and traditional methods, which are manual and time-consuming, are sometimes incomplete. This is particularly concerning for HVAC controls, where an analyst would first identify all relevant sensor measurements from the building management system, cross-reference them with design drawings, and then compile a sequence of operations to test before implementation and analysis. This process becomes harder to manage as the system scales. In this study, we demonstrate it is possible to enhance HVAC equipment and control sequence commissioning by using a metadata schema called Brick in the performance test. The Brick schema allows for querying required measurement points from the BMS in a standardized,...

Quantifying Office Building HVAC Marginal Operating Carbon Emissions and Load Shift Potential: A Case Study in California

Tue, 7 Jan 2025 00:00:00 +0000

The operational carbon emissions intensity of the electricity used in a building is commonly treated as a fixed value but grid carbon emissions factors have temporal and geographical variations, which makes building operating emissions dependent on when and where electricity is used. Grid electricity carbon characteristics can be quantified by either average or marginal emission rates, leading to an increasing debate about which metric provides more accurate results for determining the effect of various decarbonization strategies. We advocate for the use of the marginal operating emissions rate (MOER) to evaluate the impacts of demand-side management because it considers the generating plants' dispatch order and is able to reflect the change in emissions induced by demand management. In this study, we examined the benefits of emission-based load-shifting strategies by first analyzing the annual temporal variations of the Northern California grid region and developed a virtual...

Field Study of Thermal Infrared Sensing for Office Temperature Control

Tue, 7 Jan 2025 00:00:00 +0000

The purpose of this paper is to evaluate the performance of a novel office temperature control system. To make occupants more comfortable with less energy, we have been developing a new system that uses an inexpensive infrared camera to evaluate occupants’ thermal sensation and optimize room temperature. The system (1) detects the positions of a person’s face, nose, and hands in a thermal image taken by an infrared camera and measures temperatures in those areas; (2) predicts thermal sensation using measured skin temperatures; and (3) adjusts an HVAC set-point temperature based on the predicted sensation to optimize occupant thermal comfort. We compared the comfort and energy performance of the new system to conventional control using a fixed setpoint of 72.0 °F (22.2 °C) in a small conference room. The results indicate that the conventional control often overcooled the occupants, whereas our system reduced cooling energy consumption and made the occupants more thermally neutral...

Robo-Chargers: Optimal Operation and Planning ofa Robotic Charging System to Alleviate Overstay

Tue, 7 Jan 2025 00:00:00 +0000

Charging infrastructure availability is a major concern for plug-in electric vehicle users. Nowadays, the limited public chargers are commonly occupied by vehicles which have already been fully charged. Such phenomenon, known as overstay, hinders other vehicles’ accessibility to charging resources. In this paper, we analyze a charging facility innovation to tackle the challenge of overstay, leveraging the idea of Robo-chargers -automated chargers that can rotate in a charging station and proactively plug or unplug plug-in electric vehicles. We formalize an operation model for stations incorporating Fixed-chargers and Robo-chargers. Optimal scheduling can be solved with the recognition of the combinatorial nature of vehicle-charger assignments, charging dynamics, and customer waiting behaviors. Then, with operation model nested, we develop a planning model to guide economical investment on both types of chargers so that the total cost of ownership is minimized. In the planning...

Field Study of Thermal Infrared Sensing for Office Temperature Control

Tue, 7 Jan 2025 00:00:00 +0000

Field Study of Thermal Infrared Sensing for Office Temperature Control

Field Demonstration of the Brick Ontology to Scale up the Deployment of ASHRAE Guideline 36 Control Sequences

Fri, 1 Sep 2023 00:00:00 +0000

Many commercial buildings have a vast network of sensors as part of their building automation systems (BAS) that allows opportunities for energy consumption and cost savings by deploying advanced control sequences. However, this resource is often underutilized since BAS are typically programmed with simple control sequences with limited potential to deliver on these opportunities. The recent availability of ASHRAE Guideline 36 (G36) with advanced HVAC control sequences supports control retrofits in existing buildings to unlock much of the savings potential. However, barriers such as the lack of standard naming convention of building assets and data points, proprietary equipment and BAS, and the inherent uniqueness of buildings and their systems prevent building stakeholders from adopting any “plug-and-play” implementation of G36. Instead, control vendors must often undertake the manual and labor-intensive point mapping process to identify a data stream’s functional and spatial...

Toward Design Automation for Building Models

Mon, 17 Jul 2023 00:00:00 +0000

Building performance simulation is an important tool in building design and operations. Its purpose is to evaluate and optimize energy use, environmental impact, and occupant comfort of buildings. However, the current state of building performance simulation tools is highly fragmented, and the models themselves can be of low quality. In this paper, we present a platform-based design paradigm for building performance models. This approach offers a standardized design flow to ensure that the models are developed in a consistent and systematic way. Addition- ally, our approach addresses the lack of model performance metrics, allowing for the quantification of model performance. We explore the design flow and model performance quantification with a case study, demonstrating the use of the platform-based design paradigm.

Skewering the silos: using Brick to enable portable analytics, modeling and controls in buildings

Mon, 5 Jun 2023 00:00:00 +0000

Skewering the silos: using Brick to enable portable analytics, modeling and controls in buildings

iSEA: IoT-based smartphone energy assistant for prompting energy-aware behaviors in commercial buildings

Wed, 29 Apr 2020 00:00:00 +0000

Providing personalized energy-use information to individual occupants enables the adoption of energy-aware behaviors in commercial buildings. However, the implementation of individualized feedback still remains challenging due to the difficulties in collecting personalized data, tracking personal behaviors, and delivering personalized tailored information to individual occupants. Nowadays, the Internet of Things (IoT) technologies are used in a variety of applications including real-time monitoring, control, and decision-making due to the flexibility of these technologies for fusing different data streams. In this paper, we propose a novel IoT-based smartphone energy assistant (iSEA) framework which prompts energy-aware behaviors in commercial buildings. iSEA tracks individual occupants through tracking their smartphones, uses a deep learning approach to identify their energy usage, and delivers personalized tailored feedback to impact their usage. iSEA particularly uses an energy-use...

Measuring 3D indoor air velocity via an inexpensive low-power ultrasonic anemometer

Mon, 20 Apr 2020 00:00:00 +0000

The ability to inexpensively monitor indoor air speed and direction on a continuous basis would transform the control of environmental quality and energy use in buildings. Air motion transports energy, ventilation air, and pollutants around building interiors and their occupants, and measured feedback about it could be used in numerous ways to improve building operation. However indoor air movement is rarely monitored because of the expense and fragility of sensors. This paper describes a unique anemometer developed by the authors, that measures 3-dimensional air velocity for indoor environmental applications, leveraging new microelectromechanical systems (MEMS) technology for ultrasonic range-finding. The anemometer uses a tetrahedral arrangement of four transceivers, the smallest number able to capture a 3-dimensional flow, that provides greater measurement redundancy than in existing anemometry. We describe the theory, hardware, and software of the anemometer, including algorithms...

Towards utilizing internet of things (IoT) devices for understanding individual occupants' energy usage of personal and shared appliances in office buildings

Mon, 23 Sep 2019 00:00:00 +0000

Energy consumption in office buildings highly depends on occupant energy-use behaviors and intervening these behaviors could function as a cost-effective approach to enhance energy savings. Current behavior-intervention techniques extensively rely on occupant-specific energy-use information at the workstation level and often ignore shared appliances. It is because an occupant typically has full responsibility for her workstation appliances energy consumption and shares the responsibility of the shared appliances energy consumption. However, understanding energy-use behavior of both workstation and shared appliances is necessary for applying appropriate behavior-intervention techniques. Despite this importance, there is still no practical and scalable method to capture personalized energy-use information of workstation and shared appliances since the conventional methods use plug-in power meters that are extremely expensive and difficult to maintain over long period of time. To...

Extracting Occupants’ Energy-Use Patterns from Wi-Fi Networks in Office Buildings

Wed, 31 Jul 2019 00:00:00 +0000

Wi-Fi networks are currently considered as an efficient and economical tool for occupancy sensing in office buildings. Studies particularly indicated that these networks could be utilized to understand/predict occupants’ energy-use patterns. Despite the value that investigating this possibility could provide for the current research, it has not been well explored how energy-use pattern information could be extracted from Wi-Fi system information. In response, this study utilizes statistical analyses to investigate the correlation of Wi-Fi flows with miscellaneous electric loads (MELs) in office buildings. MELs account for more than one-third of office-building energy consumption and are the best representative of occupants’ energy-use patterns. In the pursuit of the objective, data from two offices were collected over a 3-month period of time. Results from the analyses show that an average 92 percent of MELs energy consumption could be predicted through the Wi-Fi flows in a building....

Performance analysis of pulsed flow control method for radiant slab system

Wed, 8 May 2019 00:00:00 +0000

We present a novel pulsed flow control method (PFM) using a two-position valve to regulate the capacity of radiant slab systems. Under PFM, the on-time duration of the valve is short (compared to all prior work, e.g. 4-minute), and fixed, while the off-time varies. We present a novel, open-source, finite difference model that assesses three-dimensional transient slab heat transfer, accounting for the transient heat storage of the pipe fluid. Sensitivity analysis results indicate the dominant factors influencing energy performance of the PFM are: on-time duration; pipe diameter; and spacing. We experimentally validated both the new control strategy and model in full-scale laboratory experiments. Compared with previous intermittent control strategies (with on-time durations over 30 min), at 50% part load the PFM reduces 27% required water flow rate and increases supply to return water temperature differential. Compared with the variable temperature control method, at 50% part load...

Machine learning approaches to predict thermal demands using skin temperatures: Steady-state conditions

Tue, 17 Jul 2018 00:00:00 +0000

Inefficient controlling strategies in heating and cooling systems have given rise to a large amount of energy waste and to widespread complaints about the thermal environment in buildings. An intelligentcontrol method based on a support vector machine (SVM) classifier is proposed in this paper. Skin temperatures are the only inputs to the model and have shown attractive prediction power in recognizingsteady state thermal demands. Data were accumulated from two studies to consider potential use for either individuals or a group of occupants. Using a single skin temperature correctly predicts 80% ofthermal demands. Using combined skin temperatures from different body segments can improve the model to over 90% accuracy. Results show that three skin locations contained enough information forclassification and more would cause the curse of dimensionality. Models using different skin temperatures were compared. Optimal parameters for each model were provided using grid search technique....

Coordinate control of air movement for optimal thermal comfort

Tue, 10 Apr 2018 00:00:00 +0000

Personally controlled air movement can maintain or enhance thermal comfort in warm environments and reduce energy consumption. Unlike controlling a personal fan, using a system of fans for multiple occupants is difficult as it is hard to find an appropriate fan speed setting that maximizes occupants’ satisfaction. Since limited work has been carried out on this issue, in this paper, a novel cooperative control approach for a system of fans is proposed to provide optimized air movement for multiple occupants. This is the first time that a system of fans is controlled cooperatively in the research of built environment. The proposed approach predicts airflow in a cost-effective manner by calibrating the fans in the real environment. The operation of the fans is optimized by minimizing the worst-case deviation between the actual air speed and the desired air speed, which can be determined based on either the PMV – SET model or the occupants’ feedback. This minimax-error problem is...

A Derivation of the GAGGE 2-Node Model

Mon, 3 Oct 2016 00:00:00 +0000

A Derivation of the GAGGE 2-Node Model

Occupant comfort, control, and satisfaction in three California mixed-mode office buildings

Thu, 5 Nov 2015 00:00:00 +0000

This report outlines the results from an occupant survey of satisfaction with thermal comfort and air quality in three California mixed-mode office buildings. Mixed-mode refers to the relatively new design strategy of explicitly integrating natural ventilation with mechanical cooling and ventilation services. Each of the research sites includes operable windows along with a complete HVAC system. Survey results indicate that access to operable windows has a significant positive impact on reported satisfaction with air movement, ventilation, and air quality. Occupants also indicate that they are more likely to use operable windows for air movement and air quality control than for temperature control.

THERM 2.0: a building component model for steady-state two-dimensional heat transfer

Thu, 5 Nov 2015 00:00:00 +0000

THERM 2.0 is a state-of-the-art software program, available without cost, that uses the finite-element method to model steady-state, two-dimensional heat transfer problems. It includes a powerful simulation engine combined with a simple, interactive interface and graphic results. Although it was developed primarily to model thermal properties of windows, it is appropriate for other building components such as walls, doors, roofs, and foundations, and is useful for modeling thermal bridges in many other contexts, such as the design of equipment.

Giving occupants what they want: guidelines for implementing personal environmental control in your building

Thu, 5 Nov 2015 00:00:00 +0000

By giving people individual control over the environmental conditions in their workplaces, designers and facility managers can help increase worker satisfaction and productivity. Task/ambient conditioning (TAC) systems allow occupants to control temperature, air flow, and in some cases lighting and sound to meet their individual needs. This technology has recently been gaining a foothold in the U.S. It is often implemented in conjunction with underfloor air distribution, which opens up opportunities for a number of efficiencies in building design and operation. In addition to improving worker satisfaction and productivity, this combined approach has the potential to improve thermal comfort and indoor air quality, reduce energy use and life-cycle building costs, and reduce floor-to-floor height in new construction. Guidelines and recommendations are presented based on recent field and laboratory research results that encourage the intelligent design, installation and operation...

Supply fan energy use in pressurized underfloor air distribution systems

Thu, 5 Nov 2015 00:00:00 +0000

This preliminary study explores the impact of various design assumptions on the supply fan energy consumption of pressurized underfloor plenum systems as compared to that of traditional overhead constant air volume (CAV) and variable air volume (VAV) systems.

The results of this study indicate that, in terms of optimizing energy efficiency, variable air volume (VAV) control of supply air is the preferred method of cooling perimeter zones of pressurized underfloor air distribution (UFAD) systems just as it is for overhead (OH) systems. Moreover, cooling fan energy consumption for underfloor VAV systems can be significantly less than that for overhead VAV systems. Results show also that constant air volume (CAV) systems can be an effective approach for zones, such as core areas, that have little load variation (assuming oversizing is minimized). For these situations a UFAD-CAV system can offer low installed cost, simplicity, and provide modest energy savings compared to...

Development of fan diagnostics methods and protocols for short term monitoring