For more information, contact

Transcription

1 ELECTROCHROMIC WINDOW TEST BED FOR ENERGY EFFICIENCY MEIE 4702 Design Team Curtis Burrowes, Leo Byun, Wing Yi Cheu Natalie Gaensbauer, Anthony Potwardowski Design Advisor Prof. Yiannis Levendis Sponsor SAGE Electrochromics Abstract The main focus of this project was to use electrochromic (EC) window technology to minimize energy usage in office buildings while accounting for individual temperature and lighting preferences. This project was a continuation of a Capstone completed last year in which a team constructed a test bed consisting of an environmental simulator for temperature and sunlight control and a model office. This year s project was a collaboration of a Mechanical Engineering (ME) and an Industrial Engineering (IE) capstone team. The ME team was responsible for completing the test bed. The tasks required were to specify and install an HVAC system for the model office, integrate sensors into a data collection system using LabVIEW, and improve the temperature control of the environmental simulator. The result of the ME Team s work was a fully operational test bed that can simulate a full range of indoor and outdoor conditions with data logging capabilities. The IE team designed a human factors test by selecting variables and set levels for different EC window tints, sunlight intensities, and indoor and outdoor temperatures. The ME team assisted the IE team in running the 81 tests, and the data from these experiments represents a full range of energy usage scenarios. The data was used by the IE team to design a control algorithm that will be integrated into a control system to customize room conditions while continuing to conserve energy. Environmental Simulator Model Office For more information, contact Y.Levendis@neu.edu

2 The Need for Project EC windows have been proven to conserve energy, but the occupants are often unhappy with the preset tints and temperatures. Existing EC Window control systems aim to minimize office building energy usage, but do not account for user preference. An informal study at the University of California-Berkeley was conducted with automatic blinds, a similar technology, and it was found that nearly 90 percent of building occupants were unhappy with the lack of control they had over the shading of the room. To put it best, one respondent to the poll wrote that while automation is great for energy efficiency; it almost never equals happy occupants. The goal of this project is to find the balance between what people find comfortable in terms of room temperature and lighting, and the greatest possible savings in heating and cooling costs realized by using the electrochromic window technology. The Design Project Objectives and Requirements The objective of this project was to have a fully operational EC Window test bed that can simulate a full range of indoor and outdoor conditions with data logging capabilities. Design Objectives An environmental simulator and a model office were developed by a Capstone team last year to test energy consumption for different personal comfort scenarios. This year s project is a collaboration of a Mechanical Engineering (ME) team and an Industrial Engineering (IE) team. Phase II of this project aims to finish the test bed and complete a series of tests with four distinct variables: indoor temperature, outdoor temperature, outdoor light level, and window tint level. Design Requirements The features added to the test bed by the ME team are a heating and cooling system to regulate temperature in the model office, an integrated data collection system, and improved temperature control on the environmental simulator. The IE team designed a series of experiments to quantify energy usage from a full range of user preference settings. The ME team assisted the IE team in completing the tests. The data from the experiment were used by the IE team to design a control algorithm that will be used to design an energy efficient control system that accounts for user preference.

3 Design Concepts Considered Industry standards and the Model Office HVAC System capabilities of the test bed The American Society of Heating, Refrigerating and Air were analyzed in order to Conditioning Engineers (ASHRAE) standard was used to calculate the specify an HVAC system for cooling and heating capacity needed to regulate the temperature in the the model office and sensors model office. For a space that is 36 x36 x32, the team calculated a for the data collection system. required cooling capacity of 910 BTU/hr (267W), and a heating capacity of 268 BTU/hr (78.5W). Sensor Specification Sensors are needed to collect data on light and temperature levels inside the test bed, as well as total energy used by the model office. The team needed the sensors to have outputs that could be read into data collection software so that the test results could be easily exported to Excel for analysis. Minimum OSHA standard for office lighting is 30 foot-candles (fc), and the maximum light intensity recorded through the EC Window was 321fc. From this information the team chose a specification of 5 500fc for the light sensor. The temperature range used for the environmental simulator was ºF, so the team needed temperature measurements in this range accurate to 1ºF. The energy usage monitor should have a resolution of 0.01 BTU/hr to collect meaningful data on the energy usage of the model office. Data Collection System Considerations for the data collection system were ease of use, ease of installation, and minimal cost. Sampling rate was not a concern, as the temperatures in the test bed change slowly and the simulated sunlight was set to a constant level. The team chose the DAQ modules and data collection software with these criteria in mind. Recommended Design Concept The test bed is able simulate a full range of indoor and outdoor temperature and lighting conditions so that energy usage can be measured for any human comfort scenario. Design Description The test bed is able to measure simulated outdoor and indoor temperatures, outdoor and indoor luminous intensity, and energy consumption of the EC window, office lighting, and office HVAC system. The team selected the ClimateRight CR-2500 Mini Portable Heater and Air Conditioner. This HVAC unit is capable of a maximum cooling capacity of 2500 BTU/hr and a maximum heating capacity of 1800 BTU/hr. It has a variable output so it can be used at 910 BTU/hr

4 in cooling mode as per the project s specification. The light sensor used was the WattStopper LS-290C. It has three possible light intensity ranges: 3-300fc, fc, or fc that the user determines, and a variable output from 0-10V. Thermocouples have an accuracy of +/ F at temperatures above 32 F and +/ F below 32 F and are used in the test bed for temperature measurement. The Kill-A-Watt TM by P3 International was selected to monitor energy consumption. The Kill-A-Watt was chosen to measure energy consumption and has a resolution of 0.01kWhr at an accuracy of ±0.2%. A schematic of the final design can be seen in the left column. The thermocouple data is collected by an OMEGA DAQ and the light sensor data is collected be a National Instruments connector block. Both of these DAQs are interfaced with LabVIEW. The total energy usage is recorded manually at the end of each experiment. The team wrote a LabVIEW VI program that records data from all inputs, exports the data to Excel. Experimental Investigations Preliminary tests were conducted to characterize the capabilities of the test bed so that a Standard Operating Procedure could be developed. This SOP was then used to conduct the test that the IE team designed to quantify energy consumption of the model office for a full range of occupant preferences. The variables of the experiment were outdoor temperature, indoor temperature, outdoor light, and the EC window tint. Three settings were chosen for each of these variables resulting in a total of 81 tests. The table to the left shows the variables and settings used in the test. The tests were completed in a randomized order, as to reduce experimental bias. The results of this test will be used to create a control algorithm that will minimize energy usage for every human comfort scenario. Key Advantages of Recommended Concept This design provides a fully functional test bed that can be used to measure energy usage for any combination of temperature and light level. The designed equipment was capable of providing data to design a control algorithm to minimize energy usage and maximize human comfort. The test be can also be easily modified in the future to test control system designs.

5 Financial Issues The test bed improvements were completed on a limited budget future costs will be attributed to the design implementation of the control system. Last year s Capstone team spent roughly $2,500 to develop the environmental simulator and model office. An additional $1550 was spent this year in order to purchase the model office HVAC system, energy usage meter, and data analysis software. This results in the test bed costing a total of $4050 to date. The team also purchased components that can be used in the final control system design by a future phase. For more information on the control system components, please see Rep 7. Recommended Improvements The next phase is to implement the control algorithm to design a control system that minimizes energy usage for every occupant temperature and lighting preference. With the results from the control algorithm, a control system that optimizes human comfort and energy usage can be designed. The ME team developed some initial plans for this control system. The controlling components of the system are a central computer and a microcontroller. The components that provide feedback are the light sensor, the temperature sensor, the motion sensor, and the energy usage monitor. The feedback will dictate the setting of the EC window, office HVAC system, the environmental HVAC system, the interior light, and the simulated sunlight. Additional information on the preliminary designs of the control system can be found in Rep 7.