Rooftop Units Research Articles

Performance evaluation and degradation assessment of crystalline silicon based photovoltaic rooftop technologies under outdoor conditions

Keeping track of field performance and degradation rate of photovoltaic panels in regions with diverse environmental exposures is critical. The objective of this paper is to determine two and half year performance characteristics and degradation rate of poly-crystalline and heterojunction with intrinsic thin layer roof-top photovoltaic units under prevailing weather conditions in the Central Anatolia region. Degradation rates of the photovoltaic units were determined through analysing the effective peak power, and the temperature corrected performance ratio of each technology. Processing of the measured data covering the test period reveals that the thin film technology offers lower degradation rate with nearly −0.1% than the poly-crystalline based technology within the range of −0.67% to −0.83%, respectively. The study allows a better understanding of variations in performance and behaviour of the output power of poly-crystalline and heterojunction with intrinsic thin layer roof-top photovoltaic units after 2.5 years of outdoor exposure.

Energy, cost, and environmental analysis of individuals and district cooling systems for a new residential city

In hot climates, the active cooling system of buildings is the main cause of high demand for electrical energy. A district cooling (DC), water-cooled chiller system based, proved the success of reducing such demand. However, this advantage of DC system was not investigated for low rise residential buildings. In this study, a comparison of the energy consumption, life-cycle-cost, and environmental impact of the DC, rooftop unit (RTU), and variable refrigerant flow (VRF) is performed. DC shows a reduced peak demand by around 50 % and 49 %, in addition to a less annual energy consumption by 55 % and 18.4 % compared to RTU and VRF systems, respectively.The life-cycle-cost analysis (LCC), which conducted in a new design city “Almutlaa” in Kuwait as a case study, indicated that the DC system is the most cost-effective system over a life cycle of 24 years. The LCC of the three systems (RTU, VRF, and DC) for the new city is 22.7, 20.8, and 17.4 billion dollars, respectively. This is means that DC saves 5.28 and 3.44 billion dollars compared to RTU and VRF, respectively. Moreover, the amount of CO₂ emission avoided using DC compared to RTU and VRF is 35,000 and 11,000 metric tons, respectively.

Hydrogen as a battery for a rooftop household solar power generation unit

Decentralization of electrical power generation using rooftop solar units is projected to develop to not only mitigate power losses along transmission and distribution lines, but to control greenhouse gases emissions. Due to intermittency of solar energy, traditional batteries are used to store energy. However, batteries have several drawbacks such as limited lifespan, low storage capacity, uncontrolled discharge when not connected to a load and limited number of charge/discharge cycles. In this paper, the feasibility of using hydrogen as a battery is analyzed where hydrogen is produced by the extra diurnal generated electricity by a rooftop household solar power generation unit and utilized in a fuel cell system to generate the required electrical power at night. In the proposed design, two rooftop concentrated photovoltaic thermal (CPVT) systems coupled with an organic Rankine cycle (ORC) are used to generate electricity during 9.5 h per day and the extra power is utilized in an electrolyzer to produce hydrogen. Various working fluids (Isobutane, R134a, R245fa and R123) are used in the ORC system to analyze the maximum feasible power generation by this section. Under the operating conditions, the generated power by ORC as well as its efficiency are evaluated for various working fluids and the most efficient working fluid is selected. The required power for the compressor in the hydrogen storage process is calculated and the number of electrolyzer cells required for the hydrogen production system is determined. The results indicate that the hybrid CPVT-ORC system produces 2.378 kW of electricity at 160 suns. Supplying 65% of the produced electricity to an electrolyzer, 0.2606 kg of hydrogen is produced and stored for nightly use in a fuel cell system. This amount of hydrogen can generate the required electrical power at night while the efficiency of electrolyzer is more than 70%.

Development and evaluation of HVAC operation schedule detection algorithm

Small- and medium-sized (<5,000 m2 or <50,000 sf) commercial buildings (SMBs) represent over 94% of the U.S. commercial building stock and consume over 1018 kJ (∼1015 Btus) of total site energy. Many of these buildings use rudimentary controls that are mostly manual, with limited scheduling capability and no monitoring or failure management. Therefore, many of the systems in these buildings are operated inefficiently and consume excess energy. SMBs typically use packaged rooftop units (RTUs) that are controlled by an individual thermostat. Studies have shown that managing set points and schedules of the RTUs will result in up to 20% energy/cost savings. Because there is no monitoring infrastructure in these buildings, deviation of actual heating, ventilation and air conditioning (HVAC) set points and schedules from expected cannot be easily inferred or detected. In this paper, a new methodology is proposed to detect HVAC operation schedules using a symbolic aggregate approximation (SAX) technique. This new method only requires a single temperature measurement (zone temperature) to infer the HVAC schedule. The method was tested and validated using field data from a number of RTUs from six buildings in different climate locations. The confusion metric was used to evaluate how well the method is able to identify the operating schedule of RTUs. Overall, the schedule detection method was successful in detecting the daily operating schedule of RTUs under summer (hot) and winter (cold) weather conditions when energy use is highest or when the RTUs are cycling ON/OFF often. The method can also distinguish different schedules and generate clusters of HVAC operating schedules.

Assessments of demand response potential in small commercial buildings across the United States

Buildings are responsible for more than 73% of the total electricity usage in the United States and have a significant contribution to peak electrical demand of the power grid. Thus, proper building demand management could improve the robustness and efficiency of grid operation and could also result in economic benefits for building owners. Almost half of the building electricity usage occurs in the commercial building sector where 60% of the installed cooling capacity is attributed to small commercial buildings employing packaged air-conditioning systems (e.g., rooftop units). Thus, understanding the demand response potential and economic benefits for the small commercial sector is of great importance. In particular, the effect of climate, building type, and utility structure on demand response potential is valuable information for building managers in identifying the most beneficial demand response strategies and for utilities in developing better utility structure rate incentives to achieve demand reduction. This article presents a simulation-based assessment approach and highlights the key assessment results for three demand response strategies—thermostat, shade, and lighting controls—across a range of building types, vintages, locations, and utility rate structures. The control performance is evaluated in terms of utility cost savings, peak demand reductions, and indoor comfort impacts in comparison to a baseline night setup strategy. The tradeoff between cost savings and comfort is also explicitly investigated. The assessment results show that the demand response controls lead to slightly worse indoor comfort compared to the baseline control, with an increase in the median percentage of people dissatisfied from 5.7% to 8.1%. However, significant demand reductions and cost savings could be achieved across all tested cases with the magnitudes dependent on the weather condition and building type. Annual electricity cost savings of 5 to 25 cents/ft2 (54 to 269 cents/m2) were demonstrated for time-of-use energy rates with demand charges, whereas the savings were relatively small, below 5 cents/ft2 (54 cents/m2) for most cases, when buildings subscribed to flat rates without demand charges.

An innovative fault impact analysis framework for enhancing building operations

The primary objective of this paper is to rank building faults based on their impacts on the building energy penalty and occupant thermal comfort penalty considering multiple faults and fault occurrence rates. A fault impact analysis framework is created by incorporating the fault model library with the whole building energy performance simulation (e.g., EnergyPlus used in this study). The fault occurrence rate is introduced as a “meta” parameter in the simulation. This framework involves three essential aspects of conducting a fault impact analysis: fault constructing, fault simulation, and fault impact analysis.A parametric sensitivity analysis was used to determine and rank the criticality of the faults considering the fault concurrence frequency, by using the deep-learning based response surface model (i.e., the multi-layer perceptron regression). The proposed fault analysis framework with ranking was tested and demonstrated for the DOE's prototype medium-sized office in four different climate zones (i.e., Atlanta, Chicago, Miami, and San Francisco) with 12,000 EnergyPlus fault simulations. A total of 129 fault modes from 41 groups of fault models were simulated for the medium-sized office case.The results demonstrate the proposed framework is robust and scalable for the fault impact analysis. The top critical fault for the medium-sized office is the fault of HVAC-Left-ON for the packaged rooftop unit, regarding the site energy, source energy, and HVAC energy. Excluding the fault of HVAC-Left-ON, the top critical faults vary significantly among the four climate zones.

Energy and Economics Analyses of Condenser Evaporative Precooling for Various Climates, Buildings and Refrigerants

Condenser evaporative pre-coolers provide a low cost retrofit option for existing packaged rooftop air conditioning application units. This paper aimed to provide a comprehensive study to assess energy savings and peak power reductions of condenser evaporative cooling. Condenser evaporative cooling leads to a lower temperature of the air entering the condenser of a rooftop unit, which results in smaller compressor power consumption. Using EnergyPlus building energy simulations, we mapped the impacts on energy savings and energy reductions at peak ambient temperatures in three building types and 16 locations with levels of pad effectiveness and demonstrated the effects on air conditioner using either R22 or R410A as refrigerants. Economics and control strategy to maximize the cost saving were also investigated. The results demonstrate that energy savings are much greater for HVAC systems with the refrigerant R410A than they are with R22, and evaporative pre-cooling provides the opportunity for annual energy savings and peak demand reductions, with significant potential in hot, dry climates. Additionally, we validated an improved mathematical model for estimating the condenser pre-cooling wet bulb efficiency which shows clear advantage over the current EnergyPlus model.

Performance maps for an air-cooled air conditioning system as a preliminary instrument for the diagnosis of evaporator fouling

During the past few decades, there has been increased interest in the development of automated approaches for detecting and diagnosing faults in air conditioning systems. Among them, thermoeconomic diagnosis is a technique which involves the use of exergy analysis. As a first step towards improving its performance, this work is focused on the thermodynamic and exergy analysis of a direct expansion air conditioning system used in small commercial building applications. The analysis was carried out by means of experimental activities on a 17.5 kW rooftop unit installed at the Herrick Laboratories, Purdue University, Indiana (USA). The system under investigation was equipped with a variable-speed compressor and variable-speed fans, thus allowing the unit to meet different loads. A detailed mapping of the performance of this system was carried out by considering the effect of the outdoor temperature and the cooling load. In addition, the effect of evaporator fouling was investigated. Results showed that poor exergy performance were achieved due to the exergy destruction occurring in the evaporator. Also, when testing evaporator fouling, results showed that this fault contributed to increase the consumption of the mechanical exergy of the air, thus allowing for an easy detection of this fault.

A regulation capacity reset strategy for HVAC frequency regulation control

The power grid has seen record demand for frequency regulation capacity in recent years due to the increased employment of renewable energy resources worldwide. Building thermal loads are flexible and thus, can be used as regulation reserves with proper control strategies. Previous studies have shown that building HVAC equipment can provide high-quality power grid regulation service with PJM performance scores of up to 0.98 and buildings’ participation in the regulation market could bring significant economic benefits for building owners. However, the power flexibility in buildings is not persistent and the available HVAC regulation capacity has significant hour-by-hour variation due to building load and other operating constraints. This paper presents a regulation capacity reset strategy for HVAC regulation control that identifies the available regulation capacity and baseline power on the fly with real-time load and operation data. The strategy relies on a steady-state HVAC performance model derived from manufacturer performance data and implements a pseudo-optimization that seeks the maximum regulation capacity while respecting all operating constraints. The proposed strategy was implemented on a variable-speed rooftop unit (RTU) and validated with laboratory tests in psychrometric chambers. The test results show that the proposed reset strategy is effective in providing consistent high-quality regulation service with negligible impact on the indoor temperature control; the zone temperature deviation from the setpoint was within 0.3 °C for all the performed tests. The reset strategy was also simulated with a prototypical building diurnal load model to quantify the integrated regulation capacity for a typical summer day. Simulation results indicate the integrated HVAC regulation capacity throughout a summer day equals approximately 1/4 of the daily electrical energy use; and the estimated daily regulation credit can offset up to 26% of the daily HVAC electricity cost based on PJM historical prices.

Laboratory-based assessment of HVAC equipment for power grid frequency regulation: Methods, regulation performance, economics, indoor comfort and energy efficiency

Real-time power supply and demand balances are critical to ensure stable power frequency and quality power services. However, the growing integration of renewable energy increasingly challenges the power infrastructure because most of the renewable resources, e.g., solar and wind energy, are intermittent and difficult to predict. To meet stringent power frequency requirements, more fast reacting frequency regulation resources are being brought online among which grid-level batteries are the dominant ones. Buildings consume more than 73% of the electricity in the US, offering significant regulation reserve for the power grid. Variable-speed air-conditioning and heat pump systems are taking an increasing share of the market due to higher efficiency requirements imposed by federal agencies. In addition to efficiency benefits, variable-speed cooling/heating systems are also perfectly suited to provide frequency regulation service since these units can modulate their power continuously over a wide range.This paper presents a methodology and case study results for laboratory-based assessments of power frequency regulation service performance for variable-speed HVAC cooling equipment. The assessment methodology involves the use of both open- and closed-loop testing in psychrometric chambers. The open-loop testing quantifies the maximum possible performance of regulation services that is building independent, whereas the closed-loop testing provides representative performance for regulation services when the equipment must maintain comfort conditions for typical “virtual” buildings. Two air-conditioning units, a variable-speed packaged rooftop unit (RTU) and a split heat pump with an after-market variable-speed retrofit, were utilized for regulation tests performed in psychrometric chambers. Both open-loop and closed-loop regulation control strategies were developed and tested for this equipment. Open-loop test results showed that variable-speed HVAC equipment can provide high quality regulation service with performance scores of up to 0.98. With PJM historical wholesale energy and regulation prices, the estimated regulation credit can offset up to 48% of the electricity price. The closed-loop regulation control was shown to have negligible impact on indoor comfort with temperature fluctuations smaller than 0.1 °C. Power regulation also did not cause any efficiency degradation for the closed-loop tests. In fact, for more humid climate conditions, the electrical input for cooling can even be reduced with regulation control due to reduced moisture removal.

Energy performance evaluation of variable-speed packaged rooftop units using field measurements and building energy simulation

Packaged air-conditioning units are widely used in commercial buildings. Most packaged units in the field are equipped with constant-speed supply fans and constant-speed compressors. Many efforts have been made to increase the operational efficiency of packaged air conditioners by retrofitting existing units with improved controls or developing innovative products with advanced designs. This paper evaluates the energy performance of a packaged unit with all variable-speed components, including the supply fan, the compressor, and the condenser fan. Both a field test and energy simulation are used to quantify the potential of energy savings from the variable-speed unit (VSU) against reference units. In the field test, the reference is a six-year-old existing unit. It was determined through monitoring for one year that the VSU had a 31% higher cooling efficiency than the reference unit. In the simulation, a retail building model was used to compare the performance between the VSU and two reference units—one representing existing units in the field and the other representing units meeting the latest energy code requirements by ASHRAE Standard 90.1. Simulation results showed that depending on the climate, the VSU can save electricity consumption (including both cooling and fan) by 45%–54% relative to the first reference and by 22%–29% relative to the second reference. These findings are valuable for building designers and contractors in selecting packaged rooftop units for both new constructions and retrofits.

CFD modeling and testing of an extended-duct air delivery system in high bay buildings

Mixing ventilation in high-bay buildings conditioned by rooftop units involves supplying and returning air near the ceiling. Several problems occur in tall spaces, such as higher return air temperatures in the summer and excessive stratification in the winter. An air delivery strategy was investigated that involves supplying and returning air at different heights depending on the season. In the summer, air is supplied low and returned just above the occupied zone to cool the occupied zone directly, letting the upper zone stratify. In the winter, air is supplied high and returned low to draw warm air down from the ceiling, thus promoting destratification. This system’s performance was investigated through a computational fluid dynamics (CFD) study. CFD modeling results reveal the effects of supply and return duct locations on room airflow and stratification generation. The room temperature gradient is less sensitive to return duct height than to supply duct height, though increasing the return duct height slightly reduced stratification and the average room temperature. CFD modeling results were validated against full-scale experimental testing results with good agreement.

Development, implementation and performance of a model predictive controller for packaged air conditioners in small and medium-sized commercial building applications

Small and medium sized commercial buildings, such as retail stores, restaurants and factories, often utilize multiple packaged air conditioners, i.e. roof top units (RTUs), to provide cooling and heating for open spaces. A conventional control approach for these buildings relies on local feedback control, where each unit is cycled on and off using its own thermostat. The lack of coordination between RTUs represents a missed opportunity for operating more efficient units when there is strong coupling between the spaces they serve and can lead to unnecessarily high electrical demand due to the inherent randomness of unit cycling. This paper presents an overall model-based predictive control (MPC) approach for RTU coordination that includes a description of the control architecture, modeling approach, implementation, and assessment. We provide results of laboratory and field tests that demonstrate the short-term and long-term performance of the MPC solution in terms of energy and demand savings.

Evaluation of flammable volume in the case of a catastrophic leak of R-32 from a rooftop unit

With the effort to use alternative refrigerants with lower global warming potential (GWP), the majority of these alternative refrigerants are classified as slightly flammable. In this paper we report on the numerical evaluation of a catastrophic leak scenario of R-32 refrigerant from a 3-ton roof top air conditioning unit (RTU) which serves a 12.2 × 9.14 × 2.4 m room. A full rupture of a 6.35 mm (¼ inch) pipe downstream of the evaporator coil is simulated. Two separate cases with refrigerant releases of 1.81 kg and 3.62 kg charge have been studied. The two charges are released in 10.2 and 20.4 s, respectively, just after the end of a unit cooling cycle. The flammable volume inside the room existed only for about 40 s with a maximum flammable volume inside the room of 1.12% of the total room volume for the 3.62 kg charge case.

Assessments of variable-speed equipment for packaged rooftop units (RTUs) in the United States

Packaged air-conditioning systems, such as rooftop units (RTUs), are widely used in small commercial buildings in the United States. Although new regulations and standards require new air-conditioning equipment to have multi-speed supply fan operation, most of the installed units employ fixed-speed supply fans. The electrical energy usage associated with constant volumetric air delivery fan systems is on the order of half the total RTU electrical energy usage because supply fans operate continuously during the occupied periods in commercial buildings for ventilation. In addition, compressors within RTUs typically feature single- or two-stage capacity controls leading to frequent unit cycling and thus, deteriorated performance in energy efficiency. This paper presents relatively comprehensive assessment results for three RTU variable-speed retrofit options: 1) retrofits of fixed-speed supply fans with variable-speed fans for single-compressor-speed units, 2) replacement of existing fixed-speed RTUs with RTUs having two-speed compressors with variable-speed supply fans and 3) retrofits of RTUs with new RTUs that incorporate variable-speed compressors and fans (indoor and outdoor). The assessment study involves parametric simulations across different building types and locations in the U.S. to understand the performance variation with respect to location and building use. Performance improvements in terms of energy efficiency, operation cost and indoor comfort delivery for the various retrofit options are demonstrated compared to conventional single-stage RTUs with constant speed supply fans. The assessment results show that all three retrofit options offer significant fan energy savings, but much smaller savings potential for compressor and condenser fan electricity consumption. The variable-speed-unit retrofit provides the highest cost savings potentials, ranging from 40 to 250 $ per rated cooling ton per year depending on the building type and location. In addition to efficiency and economic benefits, the two-stage-unit and variable-speed-unit retrofits also lead to improved indoor humidity regulation performance due to reduced unit cycling.

Comparison Evaluations of VRF and RTU Systems Performance on Flexible Research Platform

The energy performance of a variable refrigerant flow (VRF) system was evaluated using an occupancy‐emulated research building in the southeastern region of the United States. Full‐ and part‐load performance of the VRF system in heating and cooling seasons was compared with a conventional rooftop unit (RTU) variable‐air‐volume system with electric resistance heating. During both the heating and cooling seasons, full‐ and part‐load conditions (i.e., 100%, 75%, and 50% thermal loads) were maintained alternately for 2 to 3 days each, and the energy use, thermal conditions, and coefficient of performance (COP) for the RTU and VRF system were measured. During the cooling season, the VRF system had an average COP of 4.2, 3.9, and 3.7 compared with 3.1, 3.0, and 2.5 for the RTU system under 100%, 75%, and 50% load conditions and resulted in estimated energy savings of 30%, 37%, and 47%, respectively. During the heating season, the VRF system had an average COP ranging from 1.2 to 2.0, substantially higher than the COPs of the RTU system, and resulted in estimated energy savings of 51%, 47%, and 27% under the three load conditions, respectively.

Field test and simulation evaluation of variable refrigerant flow systems performance

This study aims to compare a performance of Variable Refrigerant Flow (VRF) system with Roof Top Unit (RTU) variable-air-volume (VAV) system through field tests and energy simulations. The field test was conducted at the same conditions as much as possible between two systems such as the installation and operating environments of heating, ventilation and air conditioning (HVAC) system including internal heat gain and outdoor conditions including buildings to compare the performance of two systems accurately. A VRF system and RTU were installed at the test building located in Tennessee Oak Ridge in the USA and the same internal heat gain was generated at the same operating time of the two systems using lighting, electric heater, and humidifier inside the building. The HVAC system was alternately operated between cooling and heating operations to acquire energy performance data and compare energy usage. Furthermore, an hourly building energy simulation model was developed with regard to the VRF system and RTU and then the model was calibrated using actual measured data. Then, annual energy consumptions of the two systems were compared and analyzed using the calibrated model. Moreover, additional analysis was conducted also when the control of discharge air temperature in the RTU was changed. The field test result showed that when energy consumptions of two systems were compared at the same outdoor conditions using the weather-normalized model, the VRF system exhibited energy reduction by 17% during cooling operation and by 74% during heating operation approximately. A comparison on the annual energy consumption using simulations showed that the VRF system reduced more energy consumption than that of the RTU by 60%. When a discharge air temperature in the RTU was controlled according to an outdoor air temperature, energy consumption of RTU was reduced by 6% in cooling temperature and 18% in heating operation, respectively. As a result, energy consumption of the VRF system was reduced more than that of the RTU by 55% approximately.

15.11: Lab testing and modelling of thermal break assemblies: Mitigating structural penetrations in building envelopes

ABSTRACTThe large temperature differentials between inside and outside spaces in Alaska (&gt;100°F) has triggered the use of thermal‐break details for envelope point protrusions for decades, mostly to prevent condensation on interior structural members. This has been done, however, using engineering judgment, and, prior to this study, no experimental or computational analysis has been conducted on the effectiveness of these details.This study outlines a series of thermal and structural tests of thermal bridges and thermal break details for steel sections protruding through the building envelope such as for canopies or rooftop mechanical units. The results of the experimental data will be correlated with thermal finite‐element models to provide insight on the modelling parameters. The results show that some details, while decreasing the potential for condensation, actually increases the overall heat flow through the detail, when compared to the control condition with no thermal break.

A self-learning algorithm for coordinated control of rooftop units in small- and medium-sized commercial buildings

With the advent of the smart grid, demand response (DR) has been implemented in many electric utility control areas to reduce peak demand in buildings during grid stress conditions. However, small- and medium-sized commercial buildings typically do not deploy a building energy management (BEM) system due to high costs of commercially available solutions. Thus, their participation in DR events implies manual control and shutting down major building loads (e.g., air conditioning systems) without considering occupant comfort. With rapid development of Internet of Things (IoT) technologies, some cost-effective IoT-based BEM systems have become available. Based on such systems, this paper presents an algorithm to automatically coordinate the operation of rooftop units (RTUs) in small- and medium-sized commercial buildings, thereby meeting the specified power limit (kW) during a DR event while taking into account occupant comfort. The proposed algorithm has been designed to intelligently learn building thermal properties using coarse-grained indoor temperature data from thermostats, thus avoiding the deployment of sophisticated sensors network. A mixed-integer linear programming model has been utilized to determine an optimal RTU control strategy during a DR event. The peak load shedding performance of the proposed strategy has been tested in an office building in Blacksburg, VA, USA. The experimental result demonstrates that the building could achieve the required peak load reduction and the computation time required by the proposed algorithm is less than 5min. This implies that with the proposed algorithm a building is capable of responding to a DR signal with a short notice, providing valuable demand-side resources for electricity capacity and ancillary markets.

Improving HVAC operational efficiency in small-and medium-size commercial buildings

Studies have shown that managing the setpoints and schedules of rooftop units (RTUs; air-conditioners and heat pumps) will result in up to 20% energy and cost savings. Another problem associated with RTUs is short cycling, i.e., when an RTU goes through ON and OFF cycles too frequently. Excessive cycling can result in decreased average efficiency (up to 10%), even if there are no physical failures in the equipment. Many small- and medium-size commercial buildings (SMBs) use rudimentary controls that are mostly manual and have limited scheduling capability and no monitoring or failure management. Therefore, many of these buildings are operated inefficiently and unnecessarily consume excess energy. SMBs typically use packaged RTUs that are controlled by individual thermostats. Ensuring the correct use of the zone setpoint and eliminating too frequent cycling of RTUs, thereby leading to persistent building operations, can significantly increase the operational efficiency of the SMBs. The work reported in this paper describes two algorithms for detecting the zone setpoint temperature and RTU cycling rate that can be deployed on low-cost infrastructure. These algorithms only require zone temperature data for detection without any additional sensor installation or supervised learning. The algorithms have been tested and validated using field data from 24 RTUs from six buildings in different climate locations. Overall, the algorithms were successful in accurately detecting the setpoints and ON/OFF cycles.