ecoenergy Innovation Initiative Research and Development Component Public Report Project: Integrated Approach to Development of a High Efficiency Energy Recovery and Intelligent Ventilation System
Contents 1 Project Snapshot... 3 2 Executive Summary... 4 3 Introduction... 5 4 Background... 6 5 Objectives... 7 5.1 Counter-flow ERV core... 7 5.2 Total ERV system with smart control... 7 5.3 In-suite ventilation measurement and verification... 7 6 Results of Project... 8 6.1 Project Achievements... 8 6.1.1 Final counter-flow ERV core prototype produced and tested... 8 6.1.2 Integrated fan coil system designed with smart controls implementation... 8 6.1.3 Confirmation of expected performance gain and energy savings... 10 6.2 Benefits... 10 6.2.1 Benefits to Canada... 11 7 Conclusion and Follow-up... 12
1 Project Snapshot Project Title Integrated Approach to Development of a High Efficiency Energy Recovery and Intelligent Ventilation System Proponent dpoint Technologies Inc Partner Enerzone Partner Tower Labs Project Highlights o Development of a new high-effectiveness counter-flow energy recovery ventilator core o Development of a new integrated fan-coil unit with ERV and smart controls to make use of economizer o Free cooling benefits around 2 C of new integrated system over standard HRV system with no smart controls Date Projected Completed July 22, 2017
2 Executive Summary A project was entered into with NRCan by dpoint Technologies (proponent), Enerzone (partner) and Tower Labs (partner) to develop a high-performing counter-flow ERV core, to be used in a to-be developed integrated fan-coil system with smart controls to take advantage of economizer mode. This system would then be monitored and verified when compared to the incumbent technology of a standard ERV system. To increase indoor air quality and reduce energy consumption the ventilation system could make use of free cooling when solar irradiation heats the indoor air but cold outside air is available to cool the space. A high-performing counter-flow ERV core was designed that took advantage of 2D heat and more importantly latent transfer. The performance of this core was validated by an independent external lab to have over 80% sensible effectiveness and over 60% total effectiveness in cooling conditions at a comparable pressure drop. This was the highest performance of any product available at the time of testing. An integrated fan-coil system that used the high-performing ERV core was designed that could make use of an economizer mode and remove the need for any extra direct expansion coils. This system could mix cold fresh outside air when available to perform cooling instead of relying on an active additional cooling system. The controls were designed to intelligently know when to take advantage of the free cooling of colder outside air when the inside air rose during the shoulder season with high incident solar irradiation. The IFC system with smart controls was reviewed by an independent engineering consulting company (RDH Building Science Consulting) to also ensure optimal operation for a specific geography, namely Toronto in this case. Monitoring and verification was carried out with a fully equipped living space and compared to the incumbent technology with a standard ERV system. During the times when economizer could be made use of during the spring of 2016, the system could cool the living space by up to 2 C. That means a reduction in external cooling load on the cooling loop. A report created by the consulting company indicated that during times it is likely that cooling is required 12% of the hours would be appropriate for free cooling in Toronto. If such a smart system would be commercialized and widely adopted or regulated, a significant portion of energy savings could be realized in climates where economizer mode make sense.
3 Introduction The integrated approach to development of a high efficiency energy recovery and intelligent ventilation system was conducted between February of 2013 and May 2016. It involved two partners, system manufacturer Enerzone and green real estate developer Tower Labs, in addition to the proponent, component manufacturer dpoint Technologies. There is always a need for a higher-performing heat and humidity exchanger to use in energy recovery ventilators. dpoint therefore partnered with Enerzone to design and provide a new high-performance counter-flow ERV core to use in their integrated fan-coil systems. As part of the original scope of the EcoEnergy initiative, a smart controls package was created by Enerzone that would modify a standard thermostat to take advantage of free cooling economizer mode when the outdoor temperature was colder than the inside air and could be used to directly cool the indoor air. This also involved making a system that could mix the required amount of air. Finally, Tower Labs developed and managed an integrated design process to evaluate the new HVAC strategy against an incumbent standard heat recovery ventilator system in a condominium demonstration. This would include the monitoring and verification of the systems to analyze the benefits of the new system. This report includes discussion of the deliverables and outcomes in the project: the research plan; design, build and test of a counter-flow ERV core; system design, HVAC control development; ventilation and monitoring system installation and commissioning, data collection, and analysis.
4 Background Current Energy Recover Ventilator (ERV) exchangers are limited in their energy recovery efficiency by the exchanger design and the permeability of membrane materials. This presents a need for exchangers with higher total energy recovery. In North America, cross-flow cores are typical, but their transfer mechanism puts a limit to how high the heat transfer can be in reasonable flow rates. To obtain higher sensible transfer, which is important for reducing heating loads in the winter, a counter-flow is a more efficient design architecture. Furthermore, current ventilation and energy recovery systems lack intelligence to operate optimally from an energy efficiency standpoint while ensuring adequate indoor air quality (IAQ). Control strategies should be based on the inputs of indoor and outdoor climate conditions, IAQ, the cost of electricity, and the comfort of the building occupant. One such situation where active cooling is used when it may not be necessary is during the shoulder seasons (spring/autumn) and the heating load from solar irradiation increases the indoor air temperature to a point where cooling is necessary, yet the outdoor air could be brought in to more passively cool the indoor environment. However, few studies have been completed to evaluate ventilation control strategies which minimize energy utilization while maintaining acceptable levels of comfort and air quality within buildings. An analysis such as this has not been completed utilizing high efficiency energy recovery systems under all seasonal conditions. This research requires an integrated approach in which the energy recovery exchanger (core), the energy recovery ventilator system, the heating, ventilation and air conditioning (HVAC) controller, and the building HVAC system are designed to function optimally together. An alternative system that would accomplish the same requirements would use two sets of fan-coils, so it is desirable to know if an ERV with economizer mode would also be more economical than this alternative. This is what sparked the need to evaluate the envisioned integrated system, and would be a new product to be able to bring to the market. The proposed approach will involve using new high efficiency ERV exchanger, system, and controller designs, implemented in an integrated approach. These are all vital components for achieving net zero energy buildings. This project will determine appropriate control strategies dependent on indoor and outdoor climate conditions, and demonstrate energy savings expected from next generation ventilation designs and approaches. The innovative concepts to be incorporated will be the reduction in need of more hydronic loops or fan coils, whereas a mixing chamber will be used to bring in the conditioned air during economizer mode.
5 Objectives The objective of this Project is to improve energy consumption and IAQ in buildings via an integrated approach to the design of ERV cores, integrated ventilation systems, and controls systems. 5.1 Counter-flow ERV core High energy recovery core with latent transfer A hybrid HRV-ERV style counter-flow core would be quicker to market, yet provide 2D transfer along a channel A novel method of creating a self-supporting corrugated structure solely out of membrane and manifolding to alternating cells was developed. Heat and moisture transfer turned out to be industry-leading, thus improving energy consumption. This would allow less heat to be used in the winter, yet retain humidity to provide comfortable indoor air quality. 5.2 Total ERV system with smart control Integrated fan coil system with counter-flow ERV core with smart control algorithm The ERV system will need to accommodate variable air flow rates and be able to mix in the direct outside cold air allowed in by the integrated controls to take advantage of free cooling The integrated fan coil system was designed to not take up much more space in a suite installation, while still being able to make use of direct outside air, and without more advanced hardware that would add cost, such as separate parts for varying conditioning adjustment. The controls on the system is able to tie into a standard thermostat and make use of outside air temperature to operate most efficiently. 5.3 In-suite ventilation measurement and verification Installation and monitoring of fan coil ERV systemin a unit Two condominium units, one on top of the other, had ERV systems installed, with one unit being a benchmark standard HRV for comparison and quantification of benefits of economizer mode Equipment and sensors were installed by an engineering firm and monitored over the shoulder (spring) season to analyze the performance of the new integrated fan coil ERV system compared to the control HRV system. The data collected showed that the integrated fan coil unit with smart controls had a measurable improvement of reducing the cooling requirement when temperatures escalated and cool air was available to be used to cool, instead of using active cooling from the cooling coil.
Cooling Heating 6 Results of Project 6.1 Project Achievements 6.1.1 Final counter-flow ERV core prototype produced and tested dpoint decided to focus efforts on a counter-flow core that was a hybrid of an HRV and ERV. After many iterations, dpoint created a final prototype that obtained positive test results of this next generation core. The results were conducted by an independent lab and showed a significant improvement in performance over the then state-of-the art. A large challenge that needed to be overcome in the design of the counter flow core was to make sure that the pressure drop was not higher than comparable cross-flow cores, so as not to increase the specific power consumption of fans to be used in the integrated system. It took three additional iterations after the original prototype to arrive at a core that had excellent energy transfer performance, but acceptable pressure drop. After each iteration, the design was analyzed to determine it the most surface area was being used. The layer spacing and channel geometry was adjusted to balance the decrease in pressure drop with the decrease in performance. As can be seen in the table below, the dpoint counter-flow ERV core has very high total effectiveness, while ensuring a reasonable pressure drop. The core will likely be run at a slightly lower flow rate in a system, so the pressure drop should be even lower, and the total effectiveness of 65% will be able to be met when operating in cooling conditions (summer). This counter-flow ERV core would then go on to be used in the fan coil system designed and built by Enerzone. Flow Rate 75 SCFM dpoint Counter Flow ERV dpoint Cross Flow ERV Competitor's Counter Flow ERV Competitor's Counter Flow HRV Sensible (%) 80.5 71.9 77.3 84 Latent (%) 55 55.5 52.9 0 Total (%) 71.8 66.2 69.0 55.3 Sensible (%) 80.6 71.9 77 83 Latent (%) 52.5 51.8 50.9 0 Total (%) 63.2 59.6 60.8 31.5 Pressure Drop (in) 0.3 0.24 0.39 0.25 6.1.2 Integrated fan coil system designed with smart controls implementation Enerzone designed and built a custom prototype system that could make use of the high effectiveness counter-flow ERV core designed to take advantage of free cooling. Enerzone also took over the design of the controls algorithm. The design of controls could make use of bypass and bring in the free cooling outside air to reduce active cooling needs. This feature distinguishes it from other systems that cannot make use of an economizer mode. The system is designed so that when the thermostat calls for cooling and the inlet water is not at an acceptable temperature for cooling operation, the Free Air Cooling Mode can use outdoor air if is at an appropriate temperature, for cooling operations.
When the thermostat calls for cooling, the Free Air ERV system will first determine if the Free Air Cooling Mode is applicable before switching to the Free Air Cooling Mode. The data collected by hygrometer H1 (see picture below) is used to determine the outdoor temperature and humidity. The controls algorithm has been designed and programming is underway so that if the control board determines that the outdoor air is at a state where cooling will be accomplished, it will initiate Free Air Cooling Mode. In Free Air Cooling Mode, valve V1 is left shut and no water enters the coil C1. The centrifugal fan CF1 then begins operating at an increased speed while fans F1 and F2 are turned on. Dampers D1 and D2 are opened to allow outdoor air to enter and exit. Hygrometer H1 is used to analyze the temperature and humidity of the incoming outside air. When the set-point of the thermostat is reached, Free Air Cooling Mode is suspended and the system returns to the standard Run Mode. Fans F3 and F4 remain off while damper D3 remains closed during this operation. It is still possible to trigger ERV HIGH SPEED MODE during this operation but the ERV will ignore this input until the Free Air Cooling Mode is complete. Through this operation, a unit that faces a sunny direction on a cool spring day can bring in the right amount of cold outside air to cool the indoor air instead of using the cooling coil.
6.1.3 Confirmation of expected performance gain and energy savings The system incorporating the ERV core and the controls system was installed and commissioned in an actual building suite that would be occupied. Installation of a standard fan coil unit with ERV for comparison was conducted on the vertically adjacent unit to validate that the results will be representative of real-world operation. It was not known ahead of time how effective an economizer mode would be when combined with a hydronic loop and compared to a standard fan-coil with ERV system. The below graph shows the ambient outdoor temperature (blue), the temperature within the datum suite(grey) and the test suite (orange), and the runtime (0-1) of the free cooling fan (light grey). Where the free-cool unit is not running in the early days the temperature of the suites is quite similar. Once the right outdoor temperatures occurred the free-cool unit was able to noticeably reduce the temperature within the suite. These data show that the running unit directly affects the indoor temperatures with up to about a 2 lowering in indoor temperature in the suite with the new system as compared to the baseline suite, based on the set points set in the control system of the prototype system. 6.2 Benefits An initial analysis by a building energy engineering firm determined that a free cooling operation could be appropriate as much as 12% of the hours of the year during times it is likely that cooling is required in Toronto based on 2014 weather data. Data from the measurement and verification portion of the project showed that the indoor temperature could be cooled up
to about a 2 C in the suite with the new system as compared to the baseline suite. This would translate into greater energy efficiency (although not quantified within the current scope) in not having to run cooling mode of the air conditioner or cooling coil, from not having to run the compressor or water pump as often. In locations where the source of electricity to run an air conditioner compressor or water pump is from a polluting source, such as coal, there would be a reduction of known pollutants, such as particulate, sulfur, nitrous oxides, mercury, etc. For those locations with clean sources of electricity, there is the reduced need to create more power plants or power sources. Operating costs of reduced active cooling would be experienced by the occupant of the unit. The cost of systems would also be reduced from not needing to have more hardware to make use of economizer mode. From the initial measurement and verification, there is a strong indication that economizer mode is advantageous, but also depends on user habits. To the enduser, there is the benefit of improved indoor air quality, and comfort. 6.2.1 Benefits to Canada Canada s extreme climate with cold/dry winters and hot humid summers drives large energy consumption for building heating, cooling, ventilation, humidification and dehumidification. A high efficiency energy recovery system will significantly reduce electricity use, natural gas consumption and greenhouse gas emissions in Canadian buildings. The technology developed can be applied to all types of buildings in Canada including houses, apartments, hospitals, schools, industrial, and commercial buildings. The Ontario Building Code was revised to regulate very high efficiency standards for singlefamily homes and the like. To obtain the 75% sensible recovery efficiency is very difficult to achieve without a counter-flow ERV. The commercialization of a formable counter-flow core will be able to address this market. Canada is also poised to adopt the highest efficiency residential system that integrates a fan coil and ERV system with smart controls to take advantage of free cooling. An analysis of the Canadian city Toronto s potential to take advantage of economizer mode as much as 12% of the hours of the year being appropriate for free cooling during times it is likely that cooling is required. With initial testing, the system proved to be able to take advantage of free cooling mode when it was available and reduce cooling requirements by as much as 2 C.
7 Conclusion and Follow-up A high-performing counter-flow ERV core was designed that took advantage of 2D heat and more importantly latent transfer. The performance of this core was validated by an independent external lab to have over 80% sensible effectiveness and over 60% total effectiveness in cooling conditions at a comparable pressure drop. This was the highest performance of any product available at the time of testing. An integrated fan-coil system that used the high-performing ERV core was designed that could make use of an economizer mode and remove the need for any extra direct expansion coils. This system was able to mix cold fresh outside air when available to perform cooling instead of relying on an active additional cooling system. The controls were designed to intelligently know when to take advantage of the free cooling of colder outside air when the inside air rose during the shoulder season with high incident solar irradiation. The IFC system with smart controls was reviewed by an independent engineering consulting company to also ensure optimal operation for a specific geography, namely Toronto in this case. Monitoring and verification was carried out with a fully equipped living space and compared to the incumbent technology with a standard ERV system. During the times when economizer could be made use of during the spring of 2016, the system was able to cool the living space by up to 2 C. That means a reduction in external cooling load on the cooling loop. A report created by the consulting company indicated that during times it is likely that cooling is required 12% of the hours would be appropriate for free cooling in Toronto. If such a smart system would be commercialized and widely adopted or regulated, a significant portion of energy savings could be realized in climates where economizer mode make sense.