Patent Application
20120295534
NOT APPLICABLE
NOT APPLICABLE
NOT APPLICABLE
The present invention relates to operations of a home energy system. More particularly, the present invention provides a method and related system for providing daily home ventilation compliant with the ASHRAE 62.2 standard. Merely, by way of example, the present invention has been applied to integrate daily home ventilation control in association with an operation of the home energy system for utilizing solar thermal energy to provide space heating and space cooling for the home with up to 80% energy usage saving for home ventilation, but it would be recognized that the invention has a much broader range of applications.
Over the past centuries, the world population of human beings has exploded. Along with the population, demand for resources has also grown explosively. Such resources include raw materials such as wood, iron, and copper and energy, such as fossil fuels, including coal and oil. Industrial countries worldwide project more increases in oil consumption for transportation and heating purposes from developing nations such as China and India. Obviously, our daily lives depend, for the most part, upon oil or other forms of fossil fuel, which are becoming scarce as it becomes depleted.
Along with the depletion of our fossil fuel resources, our planet has experienced a global warming phenomena, known as “global warming,” and brought to our foremost attention by our former Vice President Al Gore. Global warming is known as an increase in an average temperature of the Earth's air near its surface, which is projected to continue at a rapid pace. Warming is believed to be caused by greenhouse cases, which are derived, in part, from use of fossil fuels. The increase in temperature is expected to cause extreme weather conditions and a drastic size reduction of the polar ice caps, which in turn will lead to higher sea levels and an increase in the rate of warming. Ultimately, other effects include mass species extinctions, and possibly other uncertainties that may be detrimental to human beings.
Much if not all of the useful energy found on the Earth comes from our sun. Generally all common plant life on the Earth achieves life using photosynthesis processes from sun light. Fossil fuels such as oil were also developed from biological materials derived from energy associated with the sun. For life on the planet Earth, the sun has been our most important energy source and fuel for modern day solar energy. Solar energy possesses many characteristics that are very desirable! Solar energy is renewable, clean, abundant, and often widespread. Accordingly, solar panels have been developed to convert sunlight into energy. Most solar energy systems today use “PV” technology. They convert sunlight directly into the electricity that you use to light your home, or power your appliances. As merely another example, solar thermal panels also are developed to convert electromagnetic radiation from the sun into thermal energy for heating homes, running certain industrial processes, or driving high grade turbines to generate electricity. In fact, solar photovoltaic panels also generate heat as a side product. Solar panels are generally composed of an array of solar (PV and/or thermal) cells, which are interconnected to each other. The cells are often arranged in series and/or parallel groups of cells in series. Accordingly, solar panels have great potential to benefit our nation, security, and human users. They can even diversify our energy requirements and reduce the world's dependence on oil and other potentially detrimental sources of energy.
Although solar panels have been used successful for certain applications, there are still certain limitations. Solar cells are often costly. Depending upon the geographic region, there are often financial subsidies from governmental entities for purchasing solar panels, which often cannot compete with the direct purchase of electricity from public power companies. Additionally, most PV solar energy systems only utilize about 15% of the captured sun's energy. The remaining energy, mostly in the form of thermal energy, remains untapped. Moreover, conventional solar energy systems are also difficult to maintain and monitor for operational accuracy. Once a solar energy system has been installed, there is simply no easy way to monitor the accuracy of energy production. In particular, a healthy home system is provided to operate an energy transfer module coupled to other traditional building utility modules to deliver solar thermal energy converted from both PV solar panels and solar thermal panels for home utility applications such as electricity supply, water heating, home heating, home cooling, and ventilation, there is no existing method to set or program the control setting for automatically adjusting building comfort in terms of heating, cooling, and ventilation for maximizing the utilization efficiency of the captured solar energy. These and other limitations are described throughout the present specification, and may be described in more detail below.
From the above, it is seen that techniques for improving operation of an integrated solar energy system are highly desired.
The present invention relates to operation of a home energy system. More particularly, the present invention provides a method for providing home ventilation compliant with an adopted ASHRAE standard 62.2 by implementing a ventilation logic in the system control program without adding additional mechanical equipments. Merely, by way of example, the present invention has been applied to perform daily home ventilation control integrated with an operation of the home energy system for utilizing solar thermal energy to provide space heating and space cooling to coordinate with the home ventilation, but it would be recognized that the invention has a much broader range of applications.
In an embodiment, the present invention provides an apparatus for providing fresh air flow into a home for efficient energy usage and conservation of energy resources. The apparatus includes a solar module associated with a building structure. The solar module is configured for producing thermal energy from a solar energy source during a first period of time daily. The apparatus further includes an air plenum structure configured with the solar module to draw fresh air from an ambient region and to transfer the fresh air to an inner space of the building structure during a second period of time daily. Additionally, the apparatus includes an energy transfer module coupled between the air plenum structure and the inner space of the building structure and configured to process and transfer the fresh air from the ambient region. Moreover, the apparatus includes a control module configured to operate the energy transfer module to deliver the fresh air into the inner space of the building structure within the second period of time to achieve a predetermined ventilation standard for the building structure and configured to maintain a substantially constant heating load or a substantially constant cooling load within the inner space of the building structure during the second period of time. The second period of time is associated with the first period of time for utilizing the thermal energy carried by the fresh air. In a specific embodiment, the energy transfer module includes at least a blower, a damper coupled to the blower, a duct configured with the inner space or an exhaust port, and one or more sensors disposed in an upstream region and a downstream region communicating with the blower. The control module further includes a computer readable memory. The computer readable memory includes a first code directed to determine a flow rate to drive the fresh air, a second code directed to adjust the damper to direct the fresh air into the inner space or exhaust, a third code directed to receive information from the one or more sensors to determine a volume of the fresh air passing through within a selected period of time.
In an alternative embodiment, the present invention provides a method for providing a ventilation control compliant with an adopted ventilation standard for efficient energy usage and conservation of energy resources. The method includes operating a home energy system to utilize solar energy within an active period and draw fresh air for providing either space heating or space cooling for a home respectively in a heating period or a cooling period. The method further includes setting a daily ventilation period as a fractional period of a day. The daily ventilation period is substantially coincident with the daily active period during a heating period for the home or a time period after the daily active period during a cooling period for the home. Additionally, the method includes determining a target volume in compliance with a ventilation standard and determining a flow rate for delivering the fresh air during the daily ventilation period. Furthermore, the method includes performing ventilation in the daily ventilation period to deliver the fresh air to an inner region of the home using the flow rate. Moreover, the method includes monitoring an accumulated total ventilation volume of the delivered fresh air until the accumulated total ventilation volume is within a vicinity of the target volume. In an specific embodiment, the method includes providing ventilation by delivering the fresh air carrying the solar thermal energy within the daily ventilation period for heating the inner region of the home during the heating period for the home, thereby providing saving up to 60% in energy usage and equipment cost for providing space heating required by home comfort setting compared to delivering the fresh air full day. In another specific embodiment, the method includes performing ventilation by delivering the fresh air cooled by radiation from the solar module to the inner region of the home within the daily ventilation period for providing flush cooling during the cooling period for the home, thereby providing saving up to 60% in energy usage and equipment cost for providing space cooling required by home comfort setting compared to delivering the fresh air full day.
In an specific embodiment, the present invention provides a method of a daily home ventilation control compliant with ASHRAE standard 62.2 for efficient energy usage and conservation of energy resources. The method includes operating a system for providing fresh air into an interior region of a building structure. The system including at least an energy transfer module coupled to a solar thermal module. The method further includes delivering a flow of the fresh air collected by the solar thermal module from an ambient region through the energy transfer module into the interior region of the building structure to provide ventilation of the interior region of the building structure. Additionally, the method includes calculating an integrated volume of the flow within a 15-minute runtime continuously for a day to record in a float data table. The method further includes determining a target volume compliant with the ASHRAE standard 62.2 for ventilation within a daily ventilation period based on an intermittent rate for delivering the flow of the fresh air. The daily ventilation period is a partial period of a day in association with an active period when solar energy is generated by the solar thermal module for heating the fresh air or a time period after the active period when radiation cooling is provided for cooling the fresh air. The active period begins at a start time and ends at an end time. Then, the method includes determining if the system is set in a heating mode or a cooling mode at the start time. If the system is determined to be set in the heating mode at the start time, the method executing the following steps for beginning the daily ventilation period from the start time to deliver the flow of the fresh air at the intermittent rate or a first flow rate, for calculating an accumulated ventilation volume based on the float data table from the start time up to a current time, and for determining if the accumulated ventilation volume is smaller than the daily ventilation target volume. Furthermore, the method includes performing ventilation in the daily ventilation period with at least the intermittent rate if the accumulated ventilation volume is determined to be smaller than the daily ventilation target volume, or cutting off ventilation if the accumulated ventilation volume is determined to be no smaller than the daily ventilation target volume or if the current time reaches the end time. If the system is determined to be set in the cooling mode at the start time, the method executing the following steps for keeping the system in the cooling mode until a predetermined time after the end time to begin the daily ventilation period to deliver the flow of the fresh air at the intermittent rate or a second flow rate, for calculating an accumulated ventilation volume based on the float data table from a start of the daily ventilation period up to a current time, for determining if the accumulated ventilation volume is smaller than the daily ventilation target volume. Moreover, the method includes performing ventilation in the daily ventilation period with at least the intermittent rate if the accumulated ventilation volume is determined to be smaller than the daily ventilation target volume, or cutting off ventilation if the accumulated ventilation volume is determined to be no smaller than the daily ventilation target volume or if the current time reaches the start time of a next active period. In a specific embodiment, if the accumulated ventilation volume is determined to be smaller than the daily target ventilation volume, the method executes the following steps respectively to deliver the flow of the fresh air using the intermittent rate if the system is set in the heating mode but not operated to provide space heating and an interior temperature is detected to be lower than an upper bound of a comfort setting, to deliver the flow of the fresh air using the first flow rate by the system operated to provide space heating, to deliver the flow of the fresh air using the intermittent rate if the system is set in the cooling mode but not operated to provide space cooling and an interior temperature is detected to be higher than a lower bound of a comfort setting, and to deliver the flow of the fresh air using the second flow rate by the system operated to provide space cooling. The first flow rate is greater than the intermittent rate the second flow rate is greater than the intermittent rate.
Still further, the present invention provides a method for performing ventilation using the base rate for 1 hour if it is determined that there has not been ventilation to the home in the past 11 hours based on the daily float data table. In yet another embodiment, the present invention still provides a ventilation method for performing a full-day ventilation using a fixed flow rate equal to a base rate compliant with the ASHRAH standard 62.2. Of course, there can be other variations, modifications, and alternatives.
Many benefits are achieved by way of the present invention over conventional techniques. For example, the present technique provides an easy way to implement a home ventilation operation using an integrated home energy system. One or more embodiments provide a method for performing intermittent ventilation in a specified ventilation period that can be substantially shorter than a full day 24 hours time and having achieved a ventilation result compliant with states adopted ventilation standard such as ASHRAE standard 62.2 and the likes for a healthy residential home. The method adds a level of ventilation control logic within a system controller configured to operate the home energy system for providing native space heating or space cooling to coordinate with the home ventilation and other utility applications. Additionally, the method provides an economic ventilation process that takes advantage of the native system operation for providing space heating and space cooling by associating the daily ventilation period to the system active period to utilize solar energy. This allows home owner who chooses the home energy system provided according to this invention for utilizing solar energy in home utility applications without need of adding extra mechanical equipments for ventilation, instead, with options for reducing the size of heating equipment and air conditioner. This method further avoids paying high energy penalty to force the system to deliver hot air into the home in cooling season or cold air into the home under space heating in a heating season, instead of using coordination of the ventilation with the native space heating and space cooling to have substantially free ventilation. In a preferred embodiment, the present method and system provides for fresh air within a home without additional cooling or heating loads or the like, which leads to increased use of energy. That is, fresh air is provided without additional energy or with less energy use. The embodiments of the invention allow 60% or more saving of energy usage for home ventilation comparing to conventional methods. In another preferred embodiment, the present method and system provides for fresh air within a home without introducing additional dusts, particles, and moistures that will affect the air quality within the interior space of the home. Depending upon the embodiment, one or more of these benefits may be achieved. These and other benefits will be described in more detail throughout the present specification and more particularly below.
Various additional objects, features and advantages of the present invention can be more fully appreciated with reference to the detailed description and accompanying drawings that follow.
The present invention relates to operation of a home energy system. More particularly, the present invention provides a method for providing daily home ventilation compliant with ASHRAE standard 62.2 and the likes by implementing a ventilation logic on the system control program without adding additional mechanical equipments. Merely, by way of example, the present invention has been applied to a healthy home in association with a home energy system configured to utilize solar energy for providing space heating/cooling coordinated with home ventilation to achieve substantially efficient energy usage and conservation of energy resources, but it would be recognized that the invention has a much broader range of applications.
As shown, the home energy system 100 (or simply stated as “the system” in the context) is installed in association with a home dwelling or a building structure 101 for providing ventilation in addition to supplying solar thermal energy for other home utility applications. The system 100 includes a system controller 140 to control an energy transfer module 120 for utilizing both electrical and thermal energy converted from solar energy of sun 10 by a solar module 110 installed on a roof of the building structure 101. In particular, the solar module 110 is a solar thermal module converting solar energy directly to thermal energy or a PV module providing thermal energy as a side product or a combination of both. The system 100 includes a plenum structure 115 directly located underneath a bottom face of the solar module 110. The plenum structure 115 is configured to draw fresh air 111 from ambient passing across the whole bottom face of the solar module 110 to carry at least partially the thermal energy generated by the solar module 110. The fresh air 111 is guided into the energy transfer module 120 via an air inlet 121.
In a specific embodiment, the system controller 140 is configured to monitor the operation of the solar module 110 with an active period for generating thermal energy (and electrical power too) from solar energy and a controlled delivery of the a flow of the fresh air through the plenum structure 115 in a coordinated manner, depending on whether the system is set in a heating or cooling mode. When the system 100 is set in heating mode and the solar module 110 actively runs to generate thermal energy, the flow of the fresh air 111 collected in the plenum structure 115 will be heated therein and can be delivered to an interior space 106 of the building structure 101 for providing both space heating and ventilation. When the system 100 is set in the cooling mode, during the active period the flow of the fresh air 111 that is heated can be directed to an exhaust port instead of being delivered into the interior space 106. While after the active period (most likely the night time) the flow of the fresh air 111 may be cooled by the solar module 110 via a radiation cooling effect and is delivered into the interior space of the building structure to cause space cooling and provide ventilation. In multiple aspects of the system applications, the flow of the fresh air 111 can be processed in the energy transfer module 120 under the control of the system controller 140 and utilized by the system to at least provide space heating, space cooling, as well as ventilation for the interior space region 106 of the building structure 101. Of course, there are many variations, alternatives, and modifications.
Referring to
In one or more embodiments, the system controller 140 is configured to communicate via a channel 145 with a thermostat 150, which is disposed at an interior space 106 of the building structure 101 and is programmed on multiple modes of operation to provide home comfort based on seasoning necessities and occupancy schedules. For example, an indoor comfort band can be set at between a high setpoint T_zone_max and a low setpoint T_zone_min. The thermostat 150 can choose to set the system 100 in a “Heat” mode or a “Cool” mode, or can be turned off (“Off” mode). The thermostat 150 includes a built-in temperature sensor that can measure a current indoor temperature T_zone and pass the information to the system controller 140 to reset the system 100 from a heating mode to a cooling mode. In case of “Off” mode (or the thermostat is not installed at all), the system controller 140 can rely on a measured ambient temperature T_ambient to compare with a pre-specified temperature value determine whether the system should be set to a heating mode or a cooling mode. For example, if T_ambient<15 C.°, the system is determined to be set in a heating mode to provide necessary home comfort.
In another embodiment, the system controller 140 sends the indoor condition information collected from the thermostat 150 via the communication channel 142 back to the energy transfer module 120. Accordingly, the energy transfer module 120 at least operates the blower 125 and the dampers 128 or 129 to control the timing and volume of the delivered airflow 161 into the interior region 106. In a specific embodiment, the energy transfer module 120 includes a number of sensors 171 and 172 that can measure the inlet/outlet temperatures and pressures for the system controller 140 to determine the mass flow through the energy transfer module 120. For example, whenever the blower 125 is running and the damper 128 is open the volume of the airflow 161 can be calculated and recorded over time. Of course, there are many variations, alternatives, and modifications.
In a preferred embodiment, the present invention provide an additional logic level to the operation control of the system 100 for providing mechanical ventilation for the healthy home energy system operated for providing space heating/cooling. The ventilation is required to be in compliance with an emerging national standard on home ventilation based on the ASHRAE standard 62.2. The advantage of the system for providing ventilation in association with providing space heating/cooling is to avoid costly options for homeowners to add additional mechanical equipments and controls. ASHRAE standard 62.2 defines the roles of and minimum requirements for mechanical and natural ventilation systems associated with the building envelope to provide acceptable indoor air quality in residential homes or low-rise building structures. The acceptable indoor air quality in this standard focuses mainly on chemical, physical, and biological substances, not the thermal comfort requirements. In a simplified aspect of this standard, to provide acceptable indoor air quality is translated to provide proper home ventilation by transferring fresh air (assuming no dust, contamination, or properly filtered) from outdoor ambient to interior zones of the building structure with a desired ventilation rate and properly exhausting poor quality indoor air out. In most cases for typical residential home and low-rise building structures, natural ventilation only is not able to satisfy the ASHRAE standard 62.2 requirement and usage of mechanical ventilation in an active airflow process involving motor-driven fan and blower is needed. Of course, embodiments of the present invention do not limit the scope of the claims herein for just satisfying the ASHRAE standard 62.2. The ventilation logic can be applied in compliance with other ventilation standard adopted for residential home in other states or regions (such as Europe, Japan, China) and standards for ventilation in industrial or public buildings.
According to the ventilation standard set in the ASHRAE standard 62.2, a base ventilation rate for an operating blower can be determined in a 24 hours/day process for performing the whole-building ventilation to bring in outdoor air continuously, depending on a floor area of the specific building and number of bedrooms. Table 1 shows a general input data
required for activating a ventilation control logic within a system operation control settings for native space heating or cooling. The parameter IAQ_ventilation_enable is binary data as a flag on whether or not the controller should enable the ASHRAE 62.2 ventilation logic. Other parameters like the house area, stories, and bedroom count are related to a specific building structure for implementing the method in the associated with a home energy system. These parameters are inputted and saved in the system controller memory as a Config.dat file. The base ventilation rate based on full-day constant ventilation can be calculated from the Config.dat parameters as:
As an example, a 200 m2 (2,000 ft2) home with 3 bedrooms would have a base ventilation rate of 0.024 m3/s (50 CFM),
However, the ASHRAE standard 62.2 also allows an alternative way of ventilation by operating a whole-building mechanical ventilation system intermittently, e.g., within a partial period daily if the ventilation rate can be adjusted instead of using a fixed Vbase. In a specific embodiment, the present invention provides a method to control the blower 125 of the energy transfer module 120 in the system 100 as an intermittent ventilation system to be operated with an increased intermittent ventilation rate over the base rate in a time period shorter than 24 hours per day, while keeping a total daily integrated ventilation volume in compliance with the ASHRAE standard 62.2. In an implementation, whenever the blower 125 is running and the damper 128 is open the system controller 140 is configured to control the energy transfer module 120 to collect multiple sensor information about the flow 161 that passes into the interior space 106 of the building structure 101. In a specific embodiment, an accumulated airflow volume over any 15-minute time period can be measured and recorded in a float data table in the system controller 140 Table 2 shows a float data file about the total airflow volume delivered to the
building structure over any daily 15-minute timestep obtained by the energy transfer module 120. This operation can be embedded in the system control program no matter the whole system is set and operated in a heating mode or a cooling mode or any time during the day. The 15-minute performance data can be collected and stored continuously in system controller memory with at least the data in the past 24 hours being kept and available for retriving.
Because intermittent ventilation is not as effective as continuos ventilation, an ‘effectiveness’ factor is deployed in the standard based on operation fraction that is defined to be a fraction period of the day during which the building structure is actually ventilated. Table 3 provides an example of the effectiveness factor as a function of the operation fraction:
As the result, the intermittent ventilation rate (Vintermittent) can be determined from the Operation Fraction (F) and effectiveness (ε) factors as:
In a specific embodiment, the system 100 is operated at a ventilation mode within a time period measured by the operation fraction F that is associated with either an active period (during daytime) for delivering a flow of fresh air carrying solar thermal energy to provide space heating or a similar time period after the active period for using the flow of fresh air for providing night-flush cooling. For a typical residential home and low-rise building structure, the active period of the system associated with thermal energy generation and delivering is about 8+ hours daily, for example, from 8:00 AM to about 4 PM. In an implementation of the present invention, the time period dedicated for ventilation, i.e. a ventilation period, can be specified as a daily fractional period up to 24 hours, represented by the operation fraction factor F. Additionally, comparing to steady full-day ventilation, a shortened ventilation period of course yields different ventilation effect. With an operation fraction factor F being set, ASHRAE standard 62.2 requires the system operation to be run an optimized intermittent ventilation with the ‘effectiveness’ factor ε mapped with the operation fraction factor F. In a specific embodiment, the ventilation period is specified substantially in association with the active period mentioned above. For example, an 8.5 hour runtime of the ventilation period is specified to run an intermittent ventilation, that gives the operation fraction factor F=0.354. Accordingly, the Vintermittent for this home can be calculated as:
The criteria for satisfying ASHRAE standard 62.2 will be a total daily integrated airflow target VTarget
In another specific embodiment, the system 100 is configured within a native operation mode to provide space heating/cooling to the interior space of the building structure during a first time period and is also enabled with a ventilation operation mode to provide ventilation during a second time period. In one or more embodiments, the ventilation mode utilizes an intermittent ventilation operation logic that is designated to associate the second time period with the first time period by coordinating the ventilation operation with the native operation for providing space heating/cooling by the system so that those operation hours are accumulated for free home ventilation. Additionally, the ventilation operation logic is implemented to avoid the highest energy penalties for performing ventilation without adding thermal loads for interior space heating/cooling. In conventional systems, the high energy penalties may be caused by accruing the system for ventilating with the coldest night air in winter (or generally in a heating season or heating period) or the hottest daytime air in summer (or generally in a cooling season or cooling period). The ventilation operation logic according to the present invention is added on top of general system control for space heating or cooling. In another specific embodiment, the ventilation operation logic is implemented such that in the heating season the ventilation period (e.g., 8.5 hours or less) starts substantially coincidentally with the beginning of the active period and in the cooling season the ventilation period starts some time after the active period has ended. Of course, the 8.5 hours ventilation period setting is just an example. For different geological regions or different climate conditions, the specified ventilation period of a healthy home in association with the active period of the system can be different, say, 10 hours, or 12 hours, or others.
It is also understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims. Further details of a specific technique for monitoring and verifying a solar-based home energy system can be found throughout the present specification and more particularly below.
As shown in
These steps are merely examples and should not unduly limit the scope of the claims herein. As shown, the above method provides a way of performing ventilation using an intermittent system to associate with a corresponding system active period within a fraction period of a day according to an embodiment of the present invention. In a preferred embodiment, the method uses a novel home energy system that uses a controlled energy transfer module coupled to a solar thermal module to perform an intermittent home ventilation that coordinates with native space heating or space cooling operation compliant with the adopted ASHRAE standard 62.2 or the likes for different geological regions or countries. One of ordinary skill in the art would recognize many other variations, modifications, and alternatives. For example, various steps outlined above may be added, removed, modified, rearranged, repeated, and/or overlapped, as contemplated within the scope of the invention.
As shown in
In step 410, the method 400 includes operating the home energy system in association with an active period to utilize solar thermal energy for providing space heating or space cooling. In an embodiment, depending on a heating season or a cooling season, the system is set and operated correspondingly in a heating mode or a cooling mode. In either mode, the system is configured to operate the solar thermal module at least within the daily active period beginning from a specified start time till an end time to generate thermal energy from solar energy source. In the heating mode, the system controller is configured to determine a flow rate for a blower of the energy transfer module to draw a flow of fresh air from ambient and control a damper to deliver the flow into the building structure. In the cooling mode, the system controller can close the damper to shut out the flow into the interior region of the home, instead, to use another damper to direct the heated flow to exhaust port during the active period, but open the damper to send the flow in for providing cooling effect during another time period (usually in the night) after the active period. The system controller monitors energy production by the solar thermal module during the active period operation and controls the processing of the collected flow inside the energy transfer module for utilizing the solar thermal energy at least partially. As an example in a heating season, the system can trigger a space heating operation within the active period to direct deliver heated flow of the fresh air from the energy transfer module into the home whenever the actual indoor temperature condition indicates a space heating is required under criteria based on corresponding home comfort settings. The daily active period is typically about 8.5 hours depending on sun rise and set time. For example, the active period is specified to start from 8:00 AM to 4:30 PM. Depending on seasoning and geological difference, the daily active period may be longer, such as 10 hours or more. Of course, there can be other variations, modifications, and alternatives.
The method 400 further includes a step 415 of setting a daily ventilation period for the home. The ventilation control logic behind the method 400 is intended to perform an intermittent ventilation in a time period that is a fractional period of a full day to take advantage of native system operations for space heating or cooling for avoiding high energy penalties while still satisfying the ASHRAE standard 62.2. The daily ventilation period can be specified as a fractional time period of 24 hours. For example, a shortened ventilation period is 8 hours, or 10 hours, up to 24 hours. The ratio of the specified ventilation period over the total 24 hours per day gives the operation fraction factor F. For example, a shortened ventilation period is set to be 8.5 hours, then F=0.354. In an embodiment, the daily ventilation period is associated with the daily active period to coordinate the ventilation with the native system operations for providing space heating or space cooling. In particular, when the system is set in the heating mode and the active period is associated with a period of time when the system is generating solar thermal energy and drawing a flow of fresh air carrying the thermal energy. The heated fresh air is capable of providing space heating to the interior region of the home. Therefore, on the one hand if the ventilation period is set substantially coincident with the daily active period, the fresh air as delivered for ventilation also provides space heating for the home during a heating season (for example, winter time), saving energy required for heating. On the other hand, the ventilation is shut down during the off time for generating solar energy, then the fresh air from cold ambient region is not delivered into the home, so as to avoid increasing the extra energy cost for heating the cold air. When the system is set to the cooling mode, it means that the heated air should be avoided to be delivered into the home. Therefore, the daily ventilation period is set to start from a time period after the active period when no solar thermal energy is generated and more preferably the solar panel is cooled and can serve as a radiation cooler for the fresh air passed by. In an example, the ventilation period is set to start in evening time, e.g. 90 minutes after the active period ends. Then the fresh air as delivered for ventilation is also providing flush cooling for the interior region of the home, saving energy usage for nominal air conditioning. More importantly, the ventilation period as set in step 415 avoids delivering heated air into the home during a period with peak cooling load, substantially reducing the energy penalty for space cooling in order to satisfy the ventilation requirement.
The method 400 additionally includes a step 420 to determine a daily ventilation target volume for ventilation within the daily ventilation period in compliance with an adopted ventilation standard. Based on the adopted ventilation standard, daily home ventilation corresponds to a process for delivering a flow of fresh air continuously with a constant flow rate for a full day. Using the ASHRAE standard 62.2 as an example, a base ventilation rate can be calculated based on a number of parameters associated with information related to home setting including at least a floor area and bedroom counts (see Table 1) stored in the system controller. By setting a daily ventilation period that is a shortened time period (vs. a full day), daily home ventilation is an intermittent ventilation for delivering the flow of fresh air using an intermittent rate. The ventilation control logic implemented in present invention is based on an integrated airflow over the full day period that is ‘equivalent’ to home ventilation performing at the intermittent rate within the shortened time period corresponding to a fraction factor F. Here the equivalence leads to a consideration of an effectiveness factor ε (see Table 3) which depends on the fraction factor F. As seen in the descriptions earlier and particularly in Eq. 3, the intermittent rate can be provided from the base rate, the fractional factor F and the effectiveness factor ε. In the example mentioned earlier, a 8.5 hours is set as daily ventilation period, the intermittent rate is determined to be 0.136 m3/s for a home with 200 m2 (2,000 ft2) floor area and 3 bedrooms under the ASHRAE standard 62.2. Then a total flow volume can be obtained by multiplying the flow rate with the ventilation time, that is, 0.136 m3/s×60 s/min×60 min/hr×8.5 hr=4,162 m3. In an embodiment, the daily ventilation target volume is determined by the total volume to deliver the air in the specified daily ventilation period using the intermittent rate. Of course, there can be other variations, modifications, and alternatives.
In step 425, the method 400 determines a flow rate for delivering the flow of the fresh air into an interior region of the building structure for ventilation during the daily ventilation period. In order to be compliant with the adopted ventilation standard, the flow rate is set to be equal to or greater than the intermittent ventilation rate required by the system to perform ventilation effectively during the specified daily ventilation period that is shorter than a full day. If the system is in a native space heating mode that operates a solar thermal module to generate solar thermal energy and draw a flow of fresh air, the system is configured to drive a blower with a flow rate to deliver the flow of fresh air carrying the solar thermal energy into the interior space of the home. The method 400 thus just uses the step 425 to set the same flow rate for performing ventilation. As a result, the ventilation takes advantage of a native system operation for space heating and the actual ventilation time may be even shorter than the specified daily ventilation time to reach the daily ventilation target volume because the flow rate is usually much higher than the intermittent rate. Alternatively, if the system is not operated in native heating mode, the method 400 uses step 425 to set the flow rate at the intermittent rate for performing the ventilation during the daily ventilation period. Of course, there can be other variations, modifications, and alternatives. In an example, the system may turn off its native operation for space heating or space cooling and a continuous ventilation mode may be executed with a constant flow rate that is equal to the base rate according to the ventilation standard for the specific home.
Through the system controller, the system ventilation logic is further implemented, step 430, to perform ventilation in the daily ventilation period to deliver the fresh air using the flow rate set in step 425. As mentioned earlier, the daily ventilation period is set to be associated with the daily active period in step 415. During a heating season for the system, the daily ventilation period is substantially coincident with the active period (typically in the day time for utilizing solar energy). In this way, the flow of the fresh air drawn by the solar thermal module and delivered from the energy transfer module carries thermal energy for providing space heating and home ventilation at the same time. In an example above, the start time for setting the blower of the energy transfer module at the intermittent rate is substantially the same as the start time of the active period for producing solar thermal energy. As the ventilation continues, the energy transfer module operates the blower with a flow rate at least no smaller than the intermittent rate. When the system is operated in a native space heating mode, the natural flow rate to deliver the flow of the (heated) fresh air can become much higher than the intermittent rate. Furthermore, the ventilation period may be cut off the same time or even earlier than the end time of the active period if the target volume of ventilation is reached so that the system avoids adding cooling load to the home energy system after the end time of the active period for performing ventilation. During a cooling season for the system the daily ventilation period is within a predetermined time period after an end of the active period. When the system is operated in a native space cooling mode, it is more energy efficient overall to avoid delivering the flow of the fresh air that may be heated by the solar thermal module during the active period. Instead, the ventilation period is set to begin at some time, e.g. 90 minutes, after the end of the active period (usually in the evening or later) to supply the flow of the fresh air that is further cooled by radiation from the solar thermal module.
The method 400 includes, step 435, monitoring an accumulated ventilation flow volume to determine if the accumulated flow volume up to a current time meets the daily ventilation target volume determined in step 420. The accumulated ventilation airflow volume can be calculated using an airflow volume performance data collected for every 15-minute runtime stored in system controller. In an example, the 15-minute runtime airflow volume performance data stored in the system controller is compared with a flow volume with the intermittent rate during the same 15 minutes. Only the smaller value among them is credited in compliance with the ASHRAE standard 62.2 and is used for summing up over the ventilation runtime to obtain the accumulated ventilation volume up to a current time. In another embodiment, the ventilation control logic under the method 400 sets the daily target volume as the criteria to cut off the ventilation. Although the shortened ventilation period has been coordinated with the active period, the actual accumulated ventilation volume may reach the target volume before the end of the active period due to operation variation, ambient climate change, indoor condition change, and system mode setting change. Of course, there can be other variations, alternatives, and modifications.
The above sequence of processes provides a method for performing an intermittent ventilation under a healthy home system in compliance with the ASHRAE standard 62.2 according to an embodiment of the present invention. As shown, the method uses a combination of steps including supplying an ambient fresh airflow carrying thermal energy (for space heating and cooling) to provide home ventilation in coordination with the native space heating or space cooling operation. Other alternatives can also be provided where steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein. Examples about implementing the present method can be found throughout the present specification and more particularly below.
The active period at least partially is specified based on a preferred period for solar module to work at its best efficiency to generate (electrical and thermal) energy out of solar energy source. The space heating operation of the system that utilizes the solar thermal energy would be preferably carried out during the active period. By associating the daily ventilation period with the active period for space heating is able to supply fresh air into the home substantially free in causing extra energy penalty. After the active period, other forms of heating may be triggered for meeting the home comfort requirement while no need to deliver cold air into the home for any ventilation purpose.
It is also understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims. Further details of a specific control technique and logic sequence for monitoring the ambient climate and indoor condition, monitoring the solar thermal module, and operating an energy transfer module in a intermittent ventilation coordinated with native space heating/cooling, can be found throughout the present specification and more particularly below.
As shown in
These steps are merely examples and should not unduly limit the scope of the claims herein. As shown, the method provides a way for ventilating the home with efficient energy usage and conservation of energy resources by a coordination between ventilation process and native space heating/cooling operation under a home energy system utilizing solar thermal energy according to an embodiment of the present invention. One of ordinary skill in the art would recognize many other variations, modifications, and alternatives. For example, various steps outlined above may be added, removed, modified, rearranged, repeated, and/or overlapped, as contemplated within the scope of the invention.
As shown in
The method 500 further executes a step 515 for delivering a flow of the fresh air collected by the solar thermal module from an ambient region. The flow of fresh air carries the solar thermal energy generated by the solar thermal module along its way through the energy transfer module into an interior region of the building structure to provide ventilation of the interior region of the building structure. The system is configured to use the energy transfer module to measure the flow volume whenever the blower (see
In another embodiment, the method 500 further includes a step 525 for activating the system controller to determine a target volume within a daily ventilation period for a compliance of an adopted ventilation standard, e.g., ASHRAE standard 62.2. The present control logic is designed to implement the intermittent ventilation by operating the system in the specified daily ventilation period ranging from a fractional time period of the full day up to 24 hours while ensuring the total ventilation air flow to be substantially equivalent to that satisfying the requirement of the adopted ventilation standard. Accordingly, the target volume for the intermittent ventilation can be determined from an intermittent rate for performing the ventilation during the daily ventilation period. By specifying the daily ventilation period, a fractional factor F is obtained and correspondingly an effectiveness factor ε can be determined (for compensating a shorter ventilation time per day with an enhanced ventilation power). In a specific embodiment, the daily ventilation period is set to be associated with an active period when solar energy is generated by the system or associated with a time period after the active period when radiation cooling is provided so that the ventilation process can be coordinated with system native operations for space heating/cooling. In particular, the active period is associated with solar thermal energy production by the solar thermal module, beginning at a start time and ending at an end time. In another specific embodiment, the intermittent rate corresponding to a specified daily ventilation period can be provided from a base rate used for continuous ventilation for a full day based on the ventilation standard. For a specific residential home or low-rise building structure, a number of home parameters include floor area, number of floors, number of bedrooms, etc. can be provided and pre-inputted into the system controller. For example, this is available in Echo™ system provided by EchoFirst, Inc. (PVT Solar, Inc.). Using the ASHRAE standard 62.2 as an example, the base rate can be calculated from the number of home parameters using Eq. 1. Further, the intermittent rate to perform ventilation within the daily ventilation period can be obtained from the equivalence relationship between the intermittent ventilation and the continuous ventilation performed with the constant base rate for a full day according to the ASHRAE standard 62.2. Therefore, a daily ventilation target volume can be determined by directly multiplying the intermittent rate with the total time in the specified ventilation period. Of course, there can by many variations, modifications, and alternatives. For example, the number of home parameters may be not available for a particular system, then a base ventilation rate will be just set to 0.030 m3/s, according to the ASHRAE standard 62.2. In an alternative embodiment, the daily ventilation period may not be a single continuous time period and can be a combination of several time periods with different start and end time.
The method 500 adds a logic level over native operation mode by enabling a ventilation mode for the system. In an embodiment, the control logic raises a flag as to whether or not the controller should enable the ASHRAE 62.2 logic. As see in Table 1, a binary parameter IAQ_Ventillation_enablence saved in the config.dat file represents the flag for ventilation control logic. For example, if IAQ_Ventillation_enablence parameter is assigned value 1, turn on the ventilation logic; if IAQ_Ventillation_enablence parameter is assigned value 0, disable the ventilation logic.
The method 500 also includes a step 530 for determining if the system is set in a heating mode or in a cooling mode. In one or more embodiments, the system setting in either a heating or cooling mode is associated with local climate condition and interior comfort requirement. This step is associated with an enablement of a native system control logic for providing space heating or space cooling and can be independent from the enablement status of the ventilation logic. In a specific embodiment, the method 500 performs the step from the start time of the active period for the day using a communication between the controller and a thermostat installed inside the home (see
The above sequence of processes provides a method for adding a level of control logic to perform ventilation on top of current native system operation, either operated for providing space heating (in a native space heating mode) or space cooling (in a native space cooling mode) according to one or more embodiments of the present invention. Other alternatives can also be provided where steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein. Further details of the present method can be found throughout the present specification and more particularly below.
As shown in
These steps are merely examples and should not unduly limit the scope of the claims herein. As shown, the above method provides a level of ventilation control logic to deliver a flow of the fresh air from ambient via the energy transfer module in a daily ventilation period which is associated with an active period within the day for the solar thermal module to generate solar thermal energy carried by the flow of the fresh air according to an embodiment of the present invention. In a preferred embodiment, the method first sets the daily ventilation period to start substantially coincidentally with the start time of the active period, then monitoring a progress of the ventilation in terms of an accumulated flow volume to compare with the daily ventilation target volume. The active period, in an example, can start from 8:00 AM and end at 4:30 PM each day. The daily ventilation period can be specified as 8.5 hours, substantially having a same start time at 8:00 AM. One of ordinary skill in the art would recognize many other variations, modifications, and alternatives. For example, various steps outlined above may be added, removed, modified, rearranged, repeated, and/or overlapped, as contemplated within the scope of the invention.
Once the system is determined to be set in the heating mode and is enabled with the ventilation logic, at the start time of ventilation the system sets the flow rate for the blower of the energy transfer module (See
V
day=Σ(Min(Vventillation,Vintermittent×60×15)) (Eq. 5)
and sums up all the values for every 15-minute time span over all ventilation runtime from the start time up to the current time.
The ventilation logic further includes a step 561 to determine if the accumulated ventilation volume is smaller than the daily ventilation target volume (see step 520). If a returned logic value of step 561 is true, it means that additional ventilation is necessary for satisfying the ventilation standard, ASHRAE standard 62.2. The method 500 now in fact triggers a loop of control operations, first executing a step 574 for continuing ventilation by setting the blower of the energy transfer module to drive the fresh air at a flow rate that is equal to or greater than the intermittent rate, then moving back to step 551 to obtain an updated value of the accumulated ventilation volume Vday, followed by performing the step 561 again. Only if the returned logic value of step 561 is False, then does the method trigger the next step 571 to cut off the ventilation. The method 500 for performing the intermittent ventilation process under the home energy system can be stopped at the step 599. Further detailed description about executing the step 574 on how to perform the ventilation throughout the specified daily ventilation period will be found below.
As shown in
These steps are merely examples and should not unduly limit the scope of the claims herein. As shown, the above method provides a level of ventilation control logic to deliver a flow of the fresh air from ambient via the energy transfer module in a daily ventilation period which is associated with a time period after the end time of the active period within the day by the system set in a cooling mode according to an embodiment of the present invention. In a preferred embodiment, the method first sets the daily ventilation period to start at a predetermined time after the end time the active period, then monitoring a progress of the ventilation in terms of an accumulated flow volume to compare with the daily ventilation target volume. The active period, as mentioned in an earlier example, can start from 8:00 AM and end at 4:30 PM each day. The start time for the daily ventilation period may be specified at 90 minutes after the end time of the active period. In the mentioned example, the daily ventilation period can be specified to be 8.5 hours, starting substantially at 6:00 PM or later and ending at 2:30 AM next day. One of ordinary skill in the art would recognize many other variations, modifications, and alternatives. For example, various steps outlined above may be added, removed, modified, rearranged, repeated, and/or overlapped, as contemplated within the scope of the invention.
Once the system is determined to be set in the cooling mode and is enabled with the ventilation logic, the system controller keeps the system in the cooling mode and wait until the active period ends to begin the ventilation operation after that. Usually, the cooling mode is set for corresponding with a hot outdoor climate condition, for example the summer time. Therefore, the ventilation control logic is designed to delay the start of ventilation until a certain time, e.g. 90 minutes or later, after the end time of the active period to deliver a flow of the fresh air with at least the intermittent rate, step 542. This ventilation control logic avoids letting the system to deliver hot ambient air into the home to cause substantial increases of the cooling load to the system. Eventually when evening comes and ambient air temperature drops, the daily ventilation period of the system can start as the system controller sets the blower of the energy transfer module at a rate no smaller than the intermittent rate Vintermittent and open the damper in the outlet (see
At any current time after starting the daily ventilation at the step 542, the ventilation control logic implemented by the system controller is monitoring the progress of the ventilation and calculating a daily integrated ventilation volume from the start time of the ventilation up to the current time. In a specific embodiment, the energy transfer module is configured to record a 15-minute performance data Vventillation of integrated airflow volume and calculate a projected airflow volume using the intermittent ventilation rate within the 15-minute time span. The control logic deduces, in step 552, an accumulated ventilation volume Vday from the start of the daily ventilation period as:
V
day=Σ(Min(Vventillation,Vintermittent×60×15)) (Eq. 6)
and sums up all the values for every 15-minute time span over all runtime from the start time up to the current time.
The ventilation logic further includes a step 562 to determine if the accumulated ventilation volume is smaller than the daily ventilation target volume (see step 520). If a returned logic value of step 562 is True, it means that additional ventilation is necessary for satisfying the ASHRAE standard 62.2. The method 500 now in fact triggers a loop of control steps, first executing a step 575 for continuing ventilation by setting the blower of the energy transfer module to drive the fresh air at a flow rate that is equal to or higher than the intermittent rate, then moving back to step 552 to obtain an updated value of the accumulated ventilation volume Vday, followed by performing the step 562 again. Only if the returned logic value of step 562 is False, then does the method trigger the next step 572 to cut off the ventilation. The method 500 for performing the intermittent ventilation process under the home energy system can be stopped at the step 599. Further detailed description about executing the step 575 on how to perform the ventilation throughout the specified daily ventilation period will be found below.
As shown in
If the logic value of step 591 (592) is False, i.e., the system is not actively providing space heating or space cooling. Then the system controller enters another logic step 595 (596) to determine if a current indoor zone temperature Tzone is either below a pre-set upper bound value Tzone
The above sequence of processes provides a method for enabling an ASHRAE ventilation mode of a home energy system to deliver fresh ambient air into a residential home or a low-rise building structure for ventilation according to an embodiment of the present invention. As shown, the method uses a combination of steps including continuously metering air flow volume delivered to the home & writing to a 15-minute float data file, determining a daily ventilation target volume compliant with the ASHRAE standard 62.2, determining if the local climate is in heating season or cooling season, and operating a ASHRAE ventilation mode if enabled. In a specific embodiment, the ventilation control logic is configured to perform ventilation using the base ventilation rate associated with the ASHRAE standard 62.2 for 1 hour if it is determined that there has not been ventilation to the home in the past 11 hours based on the daily float data table. In another specific embodiment, the ventilation control logic is configured to operate the system to perform ventilation in a full day 24 hours with the base ventilation rate determined from the climate and home-specific parameters including home area and bedroom counts for satisfying the ASHRAE standard 62.2. In yet another specific embodiment, the ventilation control logic is configured to be applied for being compliant with other ventilation standards adopted by different countries, international organizations, and regional governments. Other alternatives can also be provided where steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13108626 | May 2011 | US |
| Child | 13269251 | US |
