Hines partnered with the Department of Energy (DOE) to develop and implement solutions to retrofit existing buildings to reduce energy consumption by at least 30% versus requirements set by Standard 90.1-2004 of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), the American National Standards Institute (ANSI), and the Illuminating Engineering Society of North America (IESNA) as part of DOE’s Commercial Building Partnerships (CBP) Program.
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This project focuses on testing and demonstrating both the hardware and Cloud versions of theSMDS under field conditions. The objectives for testing and demonstrating the hardware are to 1) characterize the performance of the SMDS technology, 2) estimate the savings-to-cost ratio for demonstration units, and 3) characterize the usability of the SMDS including ease of installation and use. The SMDS provides information to the user, but to realize savings, actions must be taken by the user. The hardware demonstrations seek to discover how effective information is in influencing actions, including which faults generate the most servicing actions by the user.
These field demonstrations are of prototype SMDS units, which have not yet completed the product development process. These early demonstration projects are critical to understanding SMDS performance in the field and to gaining a better understanding of the potential performance or user interface enhancements needed in the next generation SMDS units. Conclusions related to the larger commercial building market, such as the incidence of performance degradation and specific faults and the energy savings resulting from addressing them are beyond the scope of this study and not compatible with the current stage of SMDS development.
The demonstration was performed separately for the hardware and Cloud versions of the SMDS. Both demonstrations involved selecting buildings, installing the required hardware (although it requires less hardware, the Cloud version requires sensors and cell modems), collecting and processing data, and viewing and tabulating results. Details of the procedures are presented later in this report.
In 2011, the U.S. Department of Energy’s Building Technology Office (DOE’s BTO), with help from the Better Buildings Alliance (BBA) members, developed a specification (RTU Challenge) for high performance rooftop air-conditioning units (RTUs) with capacity ranges between 10 and 20 tons (DOE 2013). Daikin’s Rebel RTU was recognized by DOE in May 2012 as first to meet the RTU Challenge specifications. This report documents the testing of a Rebel unit and a standard reference unit in the field and compares the seasonal efficiency of the two units.
The goal of the RTU Challenge demonstration was to estimate the seasonal performance of the RTU Challenge unit and the annual savings that could be achieved by installing the challenge unit instead of an alternate standard unit. The demonstration took place at two grocery stores located in New Smyrna Beach and Port Orange, Florida. The Rebel unit was installed as a replacement of an existing unit in July 2013 at the New Smyrna Beach store. The reference unit was an existing rooftop unit in the Port Orange store that is about 6 years old. The reference unit had two compressors for staged cooling and a constant-speed supply fan. Both units had the same rated cooling capacity of 7.5 tons and served each store’s office spaces with similar footprints.
A set of sensors were used to measure the dry-bulb temperature and the relative humidity for the outdoor-air, the return-air, the mixed-air, and the supply-air. RTU total power consumption was also measured using a power transducer. These sensor measurements, together with a number of control signals were monitored at 1-minute intervals from August 2013 to September 2014.
The average daily energy efficiency ratio (EER) was computed for each unit using the monitored data. The ratio of the average EER for the two units varied between 0.9 and 2.4. The Rebel unit had a higher daily EER than the reference unit for almost all days. The EER ratio increased as the daily average outdoor-air temperature decreased, as expected. This means that RTUs with variable-speed compressors and variable-speed fans, like Rebel, had better part-load efficiencies than units using constant speed supply fans and ON/OFF controls for compressors. The average of the daily EER ratio for all days was approximately 1.38, which means that on average, the daily EER of the Rebel unit was 38% higher than that of the reference unit.
In addition to daily EER, the seasonal cooling efficiency was also calculated over the entire monitoring period. Over the 12-month period, the reference unit and the Rebel unit had seasonal EERs of 8.3 and 10.9, respectively. The Rebel unit’s seasonal EER was about 31% higher than the reference unit. This result was slightly lower than the findings from our previous simulation work, which estimated that in hot and humid climates, Rebel would consume about 40% less electricity than a RTU with a constant-speed supply fan and a single-stage mechanical cooling. Possible reasons for this difference included: 1) the load that the two units in the field served were different, while the two units in the simulation served the same load; and 2) the reference unit had higher operating efficiency than the number used in the simulation runs.
The annual energy savings from the rooftop unit replacement with Rebel was about 16,000 kWh, which translated to roughly 3.8 years in simple payback.
It was a challenge to find two units running in two different spaces that had served similar cooling loads. Although two grocery stores with similar layouts were selected, the monitored data showed that they had noticeably different load profiles. Therefore, absolute energy savings between the two units could not be calculated. If the absolute savings measurement were desirable, then the existing RTU will have to be monitored for 1 year, followed by a year of monitoring of the Rebel unit after it replaces the existing RTU.
Other issues related to the installation of the Rebel unit included:
-The Rebel unit came with a different base footprint from the existing Lennox unit. Although a curb adapter was provided, it left the unit suspended over the front side of the base, and was ultimately supported by blocks.
-Although the new Rebel unit was considerably heavier than the unit it replaced, no roof reinforcement was needed.
The store that had the Rebel unit reported no comfort issues either positive or negative. The Rebel unit had a Micro Tech III controller, which was not compatible with the existing Emerson E2 BX controller, or the Emerson building automation system (BAS). Emerson had an application for the Micro Tech II controller but not for Micro Tech III. Therefore, the store had to install an output board with a set of dry contacts to control the RTU indoor fan. They also had to add an interface to monitor the indoor fan “On/Off” status and the supply/return temperatures, but they could not control any cooling/heating/speed control functions. All operations were controlled directly by the Micro Tech III controller in the unit with input from the zone temperature sensor.
The start-up and commissioning of the Rebel was challenging because the local Daikin distributor who installed the unit had very little experience in installing these new units. In addition, the controller had many features with a large instruction/operation manual, which made it difficult to properly configure. It took the distributor a couple of trips to configure the unit correctly, but after it was configured, the unit, as well as its metering and monitoring system worked as expected. Over the last 12-month period, maintenance requirements for this unit were similar to the other units.
The Smart Monitoring and Diagnostic System (SMDS) is a low-cost technology that helps building owners and managers keep rooftop air conditioner and heat pump units (RTUs) operating properly at peak efficiency. The SMDS technology has the potential to significantly benefit small commercial buildings, which predominately use RTUs for space conditioning. Through the Better Buildings Alliance, a field demonstration was conducted at four sites using two SMDS prototypes. This case study provides a summary of the field demonstration results.
The full report is available at: https://buildingdata.energy.gov/cbrd/resource/1927
In FY14, BTO funded PNNL to develop and integrate AFDD methods for both air-side and refrigerant-side fault detection and diagnostics with one of the leading advanced RTU controllers sold in the market today. The work also includes testing and validating the integrated solution in the field. If the results from the field demonstrations show reliable fault diagnostics, it will encourage utilities to provide incentives to pursue the integrated technology because it makes the retrofit controller more cost effective and could make market adoption of the retrofit controller even more attractive to building owners.
Seven AFDD algorithms were developed, deployed and tested on the RTU controller for detecting and diagnosing faults with RTU economizer and ventilation operations using sensors that are commonly installed for advanced control purposes.
In 2011, the U.S. Department of Energy’s Building Technology Office (DOE’s BTO), with help from the Better Buildings Alliance (BBA) members, developed a specification (RTU Challenge) for high performance rooftop air-conditioning units with capacity ranges between 10 and 20 tons (DOE 2013). In April 2013, Carrier’s 10-ton WeatherExpert unit model was recognized by DOE to have met the RTU Challenge specifications. Carrier also committed to have its entire line of WeatherExpert models for commercial buildings compliant with integrated energy efficiency ratio (IEER) meeting the RTU Challenge requirement. This report documents the development of part-load performance curves and their use with the EnergyPlus simulation tool to estimate the potential savings from the use of WeatherExpert units compared to other standard options.
A detailed EnergyPlus model was developed for a prototypical big-box retail store. The model used the performance curves from the new model along with detailed energy management control code to estimate the energy consumption of the prototypical big-box retail store in three locations. The energy consumption by the big-box store was then compared to a store that used three different reference units. The first reference unit (Reference 1) represents existing rooftop units (RTUs) in the field, so it can be considered the baseline to estimate potential energy savings from other RTU replacement options. The second reference unit (Reference 2) represents RTUs in the market that just meet the current (2015) Federal regulations for commercial equipment standards, so it can be used as the baseline to estimate the potential for energy savings from WeatherExpert units in comparison with new RTUs that meet the minimum efficiency requirements. The third reference unit (Reference 3) represents units that meet ASHRAE 90.1-2010 requirements. For RTUs with cooling capacity greater than 11,000 Btu/h, ASHRAE 90.1-2010 (ASHRAE 2010) requires two-speed fan control or variable-speed fan control.
The following conclusion can be drawn about the comparison of energy cost for WeatherExpert unit compared to the three reference units:
• Using Reference 1 as the baseline, WeatherExpert units result in about 45% lower heating, ventilation and air conditioning (HVAC) energy cost in Houston, 55% lower cost in Los Angeles, and 35% lower cost in Chicago. The percentage savings of electricity cost is more than 50% for all three locations.
• Using Reference 2 as the baseline, WeatherExpert units result in about 39% lower HVAC energy cost in Houston, 52% lower cost in Los Angeles, and 32% lower cost in Chicago. The percentage savings of electricity cost is 44%, 55%, and 57%, respectively for the three locations.
• Using Reference 3 as the baseline, WeatherExpert units result in about 25% lower HVAC energy cost in Houston, 35% lower cost in Los Angeles, and 18% lower cost in Chicago. The percentage savings of electricity cost is 29%, 38%, and 37%, respectively.
Based on the simulation results, the WeatherExpert RTU Challenge unit, if widely adopted, could lead to significant energy, cost and emission reductions. Because the cost of these units was not available and because the costs would be specific to a given installation, no attempt was made to estimate the potential payback periods associated with any of the three reference scenarios. However, if the incremental cost relative to any of the three reference cases is known, one can easily estimate a simple payback period.
Overview of common commercial building Heating, Ventilating, and Air-conditioning (HVAC) systems as they relate to energy code requirements. Learn about the most common HVAC systems and equipment, along with energy-related components and controls. Several important energy code requirements will be reviewed, including what to look for in the field or on plans.
In 2011, the U.S. Department of Energy’s Building Technology Office (DOE’s BTO), with help from the Better Buildings Alliance (BBA) members, developed a specification (RTU Challenge) for high performance rooftop air-conditioning units (RTUs) with capacity ranges between 10 and 20 tons. Daikin’s Rebel RTU was recognized by DOE in May 2012 as the first to meet the RTU Challenge specifications. A study was commissioned to compare the Rebel unit with a standard reference unit in the field. The goal of the RTU Challenge demonstration was to estimate seasonal performance of the RTU Challenge unit and the annual savings that can be achieved by installing the Rebel unit instead of an alternate standard unit. This case study details this demonstration.
This guide primarily applies to facility managers and energy managers of large existing office buildings larger than 100,000 square feet, but also includes considerations for small and medium office buildings. By presenting general project planning guidance as well as financial payback metrics for the most common energy efficiency measures, this guide provides a practical roadmap for effectively planning and implementing performance improvements for existing buildings.
Retail buildings in the U.S. are second only to office buildings in total energy consumption and represent approximately 13% of energy use in commercial buildings nationwide. The Advanced Energy Retrofit Guide for Retail Buildings presents general project planning guidance as well as more detailed descriptions and financial payback metrics for the most important and relevant energy efficiency measures to provide a practical roadmap for effectively planning and implementing performance improvements in existing buildings. This guide is primarily designed for facility managers and energy managers of existing retail buildings of all sizes.