阅读说明：本技术 用于监测通过建筑物围护结构的空气泄漏并控制通风系统的方法和系统 (Method and system for monitoring air leakage through building envelope and controlling ventilation system ) 是由 比约纳尔·利 佩尔·马格纳·赫尔塞思 于 2020-02-10 设计创作，主要内容包括：用于基于建筑物围护结构内部和外部之间的气压差的测量来估计能量损失或控制建筑物中的通风的方法和系统。测量的差值可用于计算空气泄漏和相应的能量损失,或用于控制通风系统,以使气压差最小化,从而使能量损失最小化。可以通过以下步骤来计算能量损失：获得通过建筑物围护结构的空气流量与围护结构的各个侧面上的气压差之间的对应关系的估计；获得在围护结构的各个侧面上的当前气压差的测量值；基于所述对应关系和所述当前气压差计算每单位时间通过围护结构的当前空气流量；以及提供计算出的每单位时间通过围护结构的当前空气流量的表示。(Methods and systems for estimating energy loss or controlling ventilation in a building based on measurements of air pressure differential between the interior and exterior of the building envelope. The measured difference can be used to calculate air leakage and corresponding energy loss or to control the ventilation system to minimize air pressure differences and thus energy loss. The energy loss can be calculated by: obtaining an estimate of a correspondence between air flow through the building envelope and air pressure differential on each side of the envelope; obtaining a measurement of a current air pressure differential on each side of the envelope; calculating the current air flow passing through the building envelope per unit time based on the corresponding relation and the current air pressure difference; and providing a representation of the calculated current air flow through the enclosure per unit time.)

1. A method of monitoring air leaks in a building, comprising:

obtaining an estimate of a correspondence between air flow through a building envelope and air pressure differential on each side of the envelope;

obtaining measurements of current air pressure differentials on respective sides of the envelope;

calculating the current air flow passing through the enclosure structure per unit time based on the corresponding relation and the current air pressure difference; and

displaying or transmitting a representation of the calculated current air flow through the enclosure per unit time.

2. The method of claim 1, further comprising:

obtaining a measurement or calculation of an absolute air pressure outside the building envelope, a humidity outside the building envelope, and a temperature outside and inside the building envelope;

calculating an energy loss due to air leakage based on the calculated current air flow through the enclosure per unit time and the measured or calculated absolute air pressure outside the building enclosure, the humidity outside the building enclosure and the temperatures outside and inside the building enclosure; and

displaying or transmitting a representation of the calculated energy loss.

3. The method of claim 2, wherein the energy loss is a result of a net flow of heat out of the building envelope resulting in an increased need for heating, or a result of a net flow of heat into the building resulting in an increased need for cooling.

4. The method of claim 2 or 3 wherein calculating the energy loss comprises calculating a heat capacity of air outside the building envelope and a temperature difference between the building envelope interior and the exterior air, and calculating the energy required to change the temperature from the exterior temperature to the interior temperature for a volume of exterior air corresponding to the calculated current air flow through the envelope per unit time.

5. The method of claim 4, wherein calculating the energy required to change the temperature comprises an adjustment indicative of an efficiency of a heating process or a cooling process.

6. The method of claim 1, further comprising:

obtaining measurements or calculations of absolute air pressure outside and inside the building envelope, air humidity outside and inside the building envelope, and temperature outside and inside the building envelope;

respectively calculating the humidity difference or absolute moisture content of the air outside and inside the building envelope;

calculating a clean water delivery through the building envelope due to air leakage based on the calculated humidity difference or absolute moisture content and the calculated current air flow through the envelope per unit time; and

displaying or transmitting a representation of the calculated moisture delivery.

7. The method of claim 6, further comprising obtaining a measurement or calculating a dew point of air on a hottest side of the enclosure; and

an alert included in the display or transmission of the representation of the calculated moisture delivery if the dew point is above a temperature on a coldest side of the enclosure and a pressure of air on a hottest side of the enclosure is high.

8. A method according to any preceding claim wherein the estimate of the correspondence between air flow through a building enclosure and air pressure differential on each side of the enclosure is obtained by measuring the air flow rate at a selected pressure differential and deriving from the measurement an estimate of the correspondence.

9. The method according to any of the preceding claims, wherein the parameters related to humidity, temperature and barometric pressure are obtained from sensors selected from the group of: a thermometer, a hygrometer, a differential air pressure sensor, and a barometer.

10. The method of claim 9, wherein at least some parameters relating to conditions external to the building envelope are obtained from a remote weather data provider.

11. A method of controlling ventilation in a building, comprising:

obtaining a measurement of a current air pressure differential on each side of the building envelope; and

controlling a ventilation system in the building to adjust the pressure differential to a value close to zero.

12. The method of controlling ventilation in a building of claim 11, further comprising:

obtaining measurements of temperatures outside and inside the building envelope; and

controlling the ventilation system such that the value close to zero is non-zero such that the air pressure on the coldest side of the enclosure is at least a predetermined threshold higher than the air pressure on the hottest side of the enclosure.

13. The method of claim 12, further comprising:

obtaining and measuring or calculating a dew point of the hottest side of the building envelope; and

only when the dew point of the hottest side of the enclosure is higher than the temperature on the coldest side of the enclosure is the gas pressure on the coldest side of the enclosure required to be at least a predetermined threshold higher than the gas pressure on the hottest side of the enclosure.

14. The method of claim 13, wherein the dew point is calculated from measurements of temperature and relative humidity.

15. The method according to any one of claims 11 to 14, wherein the parameters relating to humidity, temperature and barometric pressure are obtained from sensors selected from the group consisting of: a thermometer, a hygrometer, a differential air pressure sensor, and a barometer.

16. The method of claim 15, wherein at least some parameters relating to conditions external to the building envelope are obtained from a remote weather data provider.

17. A system for measuring air leakage in a building, comprising:

a computerized control system comprising: a communication interface enabling the control system to receive and transmit sensor data and data derived from sensor data; a memory holding a model representing an estimate of correspondence between air flow through a building envelope and air pressure differential on each side of the envelope; and a processor capable of calculating a current air flow through the enclosure per unit time based on the received sensor data and the model;

a differential pressure sensor configured to measure air pressure differential on each side of the enclosure and transmit resulting sensor data to the control system; and

a communication interface or user interface for transmitting or displaying a representation of the air flow calculated by the processor.

18. The system of claim 17, further comprising:

a sensor or a communication link to a sensor, the sensor selected from the group consisting of: a thermometer, a hygrometer, a differential air pressure sensor, and a barometer; and

wherein the memory further holds instructions that enable the processor to calculate an energy loss due to air leakage based on the calculated current air flow through the enclosure per unit time and data received from the sensors or data calculated based on data received from the sensors, the data being representative of absolute air pressure outside the building enclosure, humidity outside the building enclosure and temperature outside and inside the building enclosure; and

the transmitting or displaying of the representation of the air flow calculated by the processor includes the calculated energy loss.

19. The system of claim 17 or claim 18, wherein the communication interface is selected from the group consisting of: a wireless communication interface, a wired communication interface, and a graphical or alphanumeric display.

20. A system for controlling air leakage in a building, comprising:

a computerized control system comprising: a communication interface enabling the control system to receive and transmit sensor data and data derived from sensor data; a memory holding instructions for controlling a fan in a ventilation system; and a processor capable of issuing control signals to the ventilation system based on the instructions; and

a differential pressure sensor configured to measure air pressure differential on each side of the enclosure and transmit resulting sensor data to the control system;

wherein the instructions are to cause the processor to control the fan such that the air pressure differential is adjusted towards a value close to zero.

21. The system of claim 20, further comprising:

a sensor or a communication link to a sensor to obtain a measurement of temperature outside and inside the building envelope; and

instructions in the memory that enable the processor to control the ventilation system such that the value close to zero is non-zero such that the air pressure on the coldest side of the enclosure is at least a predetermined threshold higher than the air pressure on the hottest side of the enclosure.

22. The system of claim 20 or claim 21, further comprising:

a sensor or a communication link to a sensor, the sensor selected from the group consisting of: a hygrometer, a barometric differential sensor, and a barometer; and

instructions in the memory that enable the processor to obtain a measurement or calculation of a dew point of a hottest side of the enclosure and issue a control signal that requires an air pressure on the coldest side of the enclosure to be at least a predetermined threshold higher than an air pressure on the hottest side of the enclosure only if the dew point of the hottest side of the enclosure is higher than a temperature on the coldest side of the enclosure.

Technical Field

The present invention relates generally to the monitoring and control of air tightness, ventilation and air conditioning of buildings.

Background

When air passes through the building envelope, the building can leak energy. Such leakage may be bi-directional and based on pressure differentials inside and outside the building envelope. Such leakage can cause considerable energy loss in heated and cooled buildings.

The most common way to solve this problem is to attempt to close or seal the opening through which air may pass. However, retrofitting old buildings to save significant energy is expensive.

An alternative is to control the air pressure inside the building to minimize the difference between the outside and inside air pressure. This approach requires knowledge of the properties of the building and the current conditions inside and outside the building.

Methods have been developed to determine the air-tightness of buildings. International standard ISO 9972 defines a fan pressurization method intended to characterize the air permeability of a building envelope or a part thereof. The criteria relate to thermal performance of the building, determination of air permeability of the building, and fan pressurization methods. The contents of this standard are incorporated herein by reference in their entirety.

Efficient utilization of air pressure control methods requires improved methods and apparatus for measuring thermal properties, and particularly air permeability, and real-time conditions affecting building performance, and systems capable of utilizing the information obtained to control ventilation and air conditioning in a manner that reduces energy losses by establishing an indoor-outdoor air pressure balance.

Disclosure of Invention

The present invention addresses these needs by providing methods and systems for monitoring air leaks in buildings and controlling ventilation systems based on such monitoring.

In a first aspect of the invention, a method is provided for: obtaining an estimate of a correspondence between air flow through the building envelope and air pressure differential on each side of the envelope; obtaining a measurement of a current air pressure differential on each side of the envelope; calculating the current air flow passing through the enclosure structure per unit time based on the corresponding relation and the current air pressure difference; and displaying or transmitting a representation of the calculated current air flow through the enclosure per unit time. The results may be displayed, for example, on a graphical user interface, or may be transmitted to a remote system for display there or further processing.

In some embodiments, the method further comprises: obtaining a measurement or calculation of absolute air pressure outside the building envelope, humidity outside the building envelope, and temperatures outside and inside the building envelope; calculating energy loss due to air leakage based on the calculated current air flow through the enclosure per unit time, and the measured or calculated absolute air pressure outside the building enclosure, humidity outside the building enclosure, and temperatures outside and inside the building enclosure; and displaying or transmitting a representation of the calculated energy loss.

The method can be used for heated buildings as well as cooled buildings. Thus, embodiments may include buildings where the energy loss is a result of an increased need for heating resulting from a net flow of heat out of the building envelope or an increased need for cooling resulting from a net flow of heat into the building.

In some embodiments of the invention, the process of calculating the energy loss comprises calculating a heat capacity of air outside the building envelope and a temperature difference between the air inside the building envelope and the outside air, and calculating the energy required to change the temperature from the outside temperature to the inside temperature for a volume of outside air corresponding to the calculated current air flow through the envelope per unit time. In some embodiments, the calculation may include an adjustment indicative of the efficiency of the heating or cooling process.

According to some embodiments of the invention, the method comprises obtaining measurements or calculations of absolute air pressure outside and inside the building envelope, air humidity outside and inside the building envelope, and temperature outside and inside the building envelope. For example, absolute air pressure may be measured on one side of the enclosure and the other side of the enclosure calculated based on the measurement and current air pressure differences measured on the sides of the enclosure. From these measurements, the humidity difference or absolute moisture content of the air outside and inside the building envelope, respectively, can be calculated. The delivery of clean water through the enclosure due to air leakage can now be calculated based on the calculated humidity difference or absolute moisture content and the calculated current air flow through the enclosure per unit time. Displaying or transmitting the resulting representation of the calculated moisture delivery.

In some embodiments of the invention, the dew point of the air on the hottest side of the enclosure is obtained by measurement or calculation. If the dew point is higher than the temperature on the coldest side of the enclosure and the air pressure on the hottest side of the enclosure is higher, an alarm is included in the display or transmission of the representation of the calculated moisture delivery.

By measuring the air flow rate at a selected pressure differential and deriving an estimate of the correspondence from the measurements, an estimate of the correspondence between the air flow rate through the building envelope and the air pressure differential on each side of the envelope can be obtained. Alternatively, other methods may be used, or the correspondence may be estimated based on knowledge of building materials and corresponding measurements in similar buildings.

In various embodiments of the invention, the parameters related to humidity, temperature and barometric pressure are obtained from sensors selected from the group consisting of: a thermometer, a hygrometer, a differential air pressure sensor, and a barometer. However, it is also consistent with the principles of the present invention to obtain at least some parameters relating to conditions outside of the building envelope from a remote weather data provider.

In another aspect of the invention, a method for controlling ventilation in a building is provided. This method is similar to the previous aspect, but according to this aspect, the energy loss is not calculated based on a known correspondence between air pressure and air leakage. Instead, the ventilation system is directly controlled in order to obtain a balance of air pressure between the inside and the outside of the enclosure. Thus, the method comprises obtaining a measurement of the current air pressure difference on each side of the building envelope and controlling a ventilation system in the building to adjust the pressure difference to a value close to zero. In some embodiments, the method further comprises obtaining temperature measurements of the exterior and interior of the building envelope, and controlling the ventilation system such that a value close to zero is non-zero, such that the air pressure on the coldest side of the envelope is at least a predetermined threshold higher than the air pressure on the hottest side of the envelope.

In other embodiments, the method includes obtaining a measured or calculated dew point for a hottest side of the enclosure, and only when the dew point for the hottest side of the enclosure is above a temperature on the coldest side of the enclosure, requiring that the air pressure on the coldest side of the enclosure be at least a predetermined threshold higher than the air pressure on the hottest side of the enclosure. The dew point may be calculated from measurements of temperature and relative humidity.

In various embodiments, different sensors may be used. The parameters related to humidity, temperature and air pressure may be obtained from sensors selected from the group consisting of: a thermometer, a hygrometer, a differential air pressure sensor, and a barometer. In some embodiments, at least some of the parameters relating to conditions external to the building envelope are obtained from a remote weather data provider.

According to yet another aspect of the present invention, a system for measuring air leakage in a building is provided. The system includes a computerized control system having: a communication interface enabling the control system to receive and transmit sensor data and data derived from the sensor data; a memory storing a model representing an estimate of correspondence between air flow through the building envelope and air pressure differential on each side of the envelope; and a processor capable of calculating a current air flow through the enclosure per unit time based on the received sensor data and the model. Further comprising a differential pressure sensor configured to measure air pressure differential on each side of the enclosure and transmit resulting sensor data to a control system; and a communication interface or user interface for transmitting or displaying a representation of the air flow calculated by the processor.

The system according to this aspect may further comprise a sensor or a communication link to a sensor, the sensor being selected from the group of: a thermometer, a hygrometer, a differential air pressure sensor, and a barometer. The memory may then further hold instructions that enable the processor to calculate an energy loss due to air leakage based on the calculated current air flow through the enclosure per unit time and data received from the sensors or data calculated based on data received from the sensors, the data being indicative of absolute air pressure outside the building enclosure, humidity outside the building enclosure, and temperature outside and inside the building enclosure. Transmitting or displaying a representation of the air flow calculated by the processor may include a calculated energy loss.

The communication interface may be selected from the group consisting of: a wireless communication interface, a wired communication interface, and a graphical or alphanumeric display.

In a fourth aspect of the invention, a system for controlling air leakage in a building is provided. Such a system may include a computerized control system comprising: a communication interface enabling the control system to receive and transmit sensor data and data derived from the sensor data; a memory holding instructions for controlling a fan in a ventilation system; and a processor capable of issuing control signals to the ventilation system based on the instructions. The differential pressure sensor may be configured to measure air pressure differential on each side of the enclosure and transmit the resulting sensor data to the control system, and the instructions will cause the processor to control the fan such that the air pressure differential is adjusted toward a value near zero.

The system according to the fourth aspect may further comprise: sensors or communication links to sensors to obtain temperature measurements outside and inside the building envelope; and instructions in the memory that enable the processor to control the ventilation system such that the value close to zero is non-zero such that the air pressure on the coldest side of the enclosure is at least a predetermined threshold higher than the air pressure on the hottest side of the enclosure.

The system according to this aspect may further comprise a sensor or a communication link to a sensor, the sensor being selected from the group of: a hygrometer, a barometric differential sensor, and a barometer; and instructions in the memory that enable the processor to obtain a measurement or calculation of a dew point of a hottest side of the enclosure and issue a control signal that requires an air pressure on the coldest side of the enclosure to be at least a predetermined threshold higher than an air pressure on the hottest side of the enclosure only if the dew point of the hottest side of the enclosure is higher than a temperature on the coldest side of the enclosure.

Drawings

The accompanying drawings illustrate exemplary embodiments of the invention and, together with the detailed description, serve to further explain various aspects and embodiments. In the attached drawings

FIG. 1 is a schematic illustration of the stacking effect in a multi-story building;

FIG. 2 is a schematic illustration of an arrangement for measuring air leakage at different air pressure differentials between the interior and exterior of a building envelope;

FIG. 3 is a similar arrangement augmented with additional sensors and a computer system that may be configured to display energy loss estimates or control a ventilation system according to the present invention;

FIG. 4 is a schematic view of sensors placed in a building with several floors or rooms;

FIG. 5 is a flow chart illustrating a method for calculating energy loss and moisture transport due to air leakage; and

fig. 6 is a flow chart illustrating a method for controlling a ventilation system.

Detailed Description

In this detailed description, exemplary embodiments of various aspects will be described. The description relies essentially on the terminology used in standards and other literature relating to building permeability and air leakage. In particular, a building may be any structure having a substantially well-defined boundary or barrier separating an interior from an exterior. Buildings are intended to include other types of man-made buildings in the strict sense of a building, including, for example, tunnels, ships, etc., as well as portions of such buildings.

A building envelope, or envelope, is a boundary or barrier that separates the interior of a building or a portion of a building from the external environment or another building or another portion of a building. The terms interior and exterior refer to the interior of the enclosure and the exterior of the enclosure, i.e. the opposite sides of the enclosure. The terms indoor and outdoor refer to spaces or areas inside and outside of an enclosure, respectively, and may be used synonymously with inside and outside.

Figure 1 shows a four storey building 10 with a building envelope 11. The enclosure includes a front door 12 and a window 13. Furthermore, the enclosure 11 will always include additional intended and unintended openings, such as vents, cracks, etc. The air inside the building envelope 11 is subjected to a number of forces including indoor and outdoor pressure differences 14, wind 15, and differences in indoor and outdoor air density caused by differences in air pressure, temperature and humidity. When the indoor air density is less than the outdoor air density, the indoor air will rise 16 and air will seep 17 into the lower floors and 18 out of the upper floors. This condition, commonly referred to as the "stack effect," is typical during colder seasons when the air inside the building 10 is warmer than the air outside the building.

The reverse stack effect occurs when the air inside the building envelope 11 is less dense than the outdoor air, which is typical when the inside air is cooled. The inside air sinks 16, the pressure difference between the inside and outside air increases and the air seeps 18 from the lower layer and through the upper layer into 17.

Somewhere between the upper and lower layers, where the outside and inside air is equal, there will be a neutral pressure level. The increase in the neutral pressure level can be controlled by varying the indoor climate.

Wind 15 typically pushes air in through the windward side of building 10 and pulls air out of the leeward side. This causes a horizontal difference in air pressure in addition to the above-mentioned vertical difference.

Passive ventilation systems take advantage of the above-described stack effect by providing vents through the building envelope 11 at appropriate locations and areas.

In addition to the above-mentioned forces caused by wind and weather, the air pressure inside the building envelope 11 is also influenced by the active ventilation system of the building. Active ventilation systems may include intake and exhaust fans (or exhaust fans), and heat exchangers configured to transfer heat from the exhausted interior air to the incoming exterior air to reduce energy losses.

The air intake and exhaust fan will have an effect on the pressure differential between the interior and exterior of the building envelope 11. The excess air intake will create a positive pressure differential between the indoor and the outside environment, pushing the indoor air out through the opening in the building envelope 11. Conversely, excessive venting can result in a corresponding negative pressure differential and pull outside air through the opening, creating ventilation and introducing unfiltered contaminated air into the building.

Those skilled in the art will readily recognize that excessive air flow through the building envelope 11 may result in energy loss, both from bleed-out of heated air and from bleed-in of cooler air, which must be heated, and from bleed-out of cooled air and from bleed-in of hot air, which must be cooled. Furthermore, when warmer humid air encounters cooler dry air, unwanted infiltration or seepage of air may cause damage from condensation.

It is impossible to control wind and weather, and although it is possible to control indoor temperature and humidity, thereby controlling air density, a desired value depends on the comfort of people who live in a building, rather than preventing air infiltration or infiltration. Thus, preventing energy loss by restricting airflow through the building envelope can be achieved in two ways: by closing an opening in the building envelope or by controlling a fan that provides intake and exhaust air. Of course, these two methods can be combined.

While strictly speaking controlling the pressure difference between the inside and the outside of the room does not require knowledge of the air tightness of the building envelope 11, such knowledge is advantageous and allows more accurate monitoring and control of the parameters. Several methods have been proposed for measuring the gas tightness, such as the international standard ISO 9972. This standard describes a fan pressurization method that can be used to measure the air permeability of a building, compare the relative air permeability of several similar buildings, and determine the amount of air leakage reduction resulting from a retrofit measure.

ISO 9972 describes several methods of creating negative or positive pressure in a building envelope to determine air permeability. Figure 2 shows a typical arrangement.

Fig. 2 shows a building 10 with a differential pressure measuring device 1 configured to measure the relative difference between indoor and outdoor air pressures. The accuracy of the pressure measurement device should be ± 1Pa in the range of 0Pa to 100Pa according to ISO 9972 standard. The temperature measuring device 2 measures indoor and outdoor temperatures. An airflow measurement system comprising an airflow meter 3 measures the airflow through the duct and a fan assembly 5 comprising a fan controller 4 configured to control the fan speed. The dimensions of the air duct and the capacity of the fan are matched so that the linear flow velocity in the air duct falls within the measurement range of the air flow meter 3. The device for measuring may be designed specifically for this purpose or may use the permanent heating, ventilation or air conditioning system fan of the building.

When the indoor pressure is lower than the outdoor pressure (the building is depressurized), air will penetrate 17 through the building envelope 11 as shown by the differential pressure measurement device 1. Conversely, if the indoor pressure is high (the building is pressurized), air will seep through the building envelope 11. ISO 9972 requires measurements to be made in increments of no more than about 10Pa over the range of applied differential pressures. The maximum pressure difference should be at least 50Pa, but 100Pa is recommended. For large buildings and air moving equipment of limited capacity this may not be possible, but the test may be effective with air pressure differentials as low as 25 Pa. Two sets of measurements are suggested during pressurization and depressurization of a building.

Other methods for making similar measurements have been proposed. Some methods suggest the use of modulated air flow, i.e. a relatively rapid change between two different flows, and the airtightness is calculated from the measured response of building pressure to the modulated flow rate. It has also been suggested to use compressed air released in pulses rather than in the form of fans, particularly for smaller buildings or rooms.

The invention does not depend on any particular method for measuring air permeability and can also work without accurate measurements, but on assumptions, for example based on knowledge of the characteristics and air permeability of buildings with similar structure and dimensions. However, accurate measurements may improve the results obtained by using the present invention.

Reference is now made to fig. 3, which shows a building having an arrangement very similar to that described above with reference to fig. 2. In addition to the components already described, the system shown in this figure includes a computer system 20 and a wireless access point 21. The wireless access point 21 is configured to establish communication with various devices included in the system. As described above, the differential pressure measurement device 1 is configured to measure the differential pressure between the indoor and outdoor environments. Here, the temperature measuring device 2 is shown as a controller connected to a plurality of sensors. In the embodiment shown in the figures, the sensors include indoor and outdoor sensors for temperature T, air pressure B and air humidity H. It should be noted that the absolute accuracy of most current air pressure sensors is not sufficient to measure the pressure difference between the interior and exterior of the enclosure 11. Thus, some embodiments include an air pressure sensor on only one side (exterior or interior) of the enclosure, and then the absolute air pressure on the other side of the body enclosure 11 can be calculated based on the measurement from that sensor and the difference measured by the differential pressure measurement device 1. The differential pressure measuring device 1 is shown here as a separate device, while the remaining sensors are connected to a common controller. Those skilled in the art will recognize that the differential pressure measurement device 1 may be connected to the same controller as the remaining sensors, and that any or all of these sensors may be connected to a separate controller. The different sensors may also be part of the same electronic circuit in a common housing and they may be specially designed as part of the system according to the invention or they may be of a general design and even configured to transmit data to more than one system.

Some embodiments may also include a heat exchanger 6 capable of cooling air flowing out of the building 10 and using the extracted heat to heat air flowing into the building. During the warm season, this process may be reversed as the building cools.

An air flow meter 3 measures the air flow rate in the air duct and a fan controller 4 controls the speed of the fans in the fan assembly 5. Performing the above method may require an air flow meter 3 to obtain a correspondence between the pressure difference and the air leakage. However, after obtaining this correspondence, no air flow meter is required to control the air pressure difference in the building. The sensors 1, 2, 3 and the fan controller 4 may include wireless communication capabilities and be configured to establish communication with the wireless access point 21. Of course, consistent with the principles of the invention, wired communication is included instead of or in addition to wireless communication capabilities.

Some embodiments of the invention may not include the airflow meter 3, the fan controller 4, and/or the fan assembly 5. Embodiments that are not configured to integrate with and control a ventilation system in a building primarily provide for monitoring of energy leakage from building 10.

The method of monitoring energy leakage may be selected from the group consisting of providing an air leakage coefficient C_LAnd estimation of the air flow index nAnd starting. C_LAnd n represents the correspondence between the air flow through the building envelope and the air pressure differential on each side of the envelope and can be determined by testing, for example by following ISO 9972. However, estimates of the coefficients based on knowledge of the structure and construction of the building, the materials used, the requirements at the time of construction, and the like may also be used. The closer the estimated value is to the actual value, the better the monitoring result, and the better the test-based estimation will be than the estimation based on the known characteristics of the building.

The air leakage rate can be expressed as a function of the differential pressure, so that the differential pressure Δ P from the differential pressure measuring device 1_rCan be used to calculate the air flow q through the building envelope_pr。

q_pr＝C_L(Δp_r)ⁿ (1)

For proper C_LThe value, which gives the air leakage rate in cubic meters per hour. Dividing by 3600 gives the air leakage rate per second.

Since water has a higher heat capacity than air, humid air will have a higher heat capacity than dry air. Thus, the energy transmitted through the enclosure due to air leakage depends on the temperature difference between the inside and outside air and the humidity of the outside air. Of course, the actual energy transfer through the enclosure will depend on the energy content of the leaking air itself. However, since the air leaking into the building is outside air and the air leaking out of the building is air that has to be replaced by outside air, which has to be heated or cooled, this is associated with a corresponding amount of energy content of the outside air.

The thermal capacity of the ambient air as a function of humidity can be approximated as

C_p，humid＝1.01+1.82·x (2)

Wherein x is the humidity ratio, given by

And wherein m_wIs the mass of water, m_dIs the mass of dry air, p_wIs the partial pressure of water vapour, p-p_wRepresents the partial pressure of dry air, denoted by p_d＝p-p_wIt is given.

In addition to this, the present invention is,

p_w＝φ·p_sat (4)

where Φ is the relative humidity, p_satIs the saturated vapor pressure of humid air, given by the tentens equation.

p_sat＝f·p_T

f＝1.0016+3.15·10^-6p-0.074p^-1 (5)

Wherein, T_cIs the temperature in degrees celsius and p is the gas pressure. It should be noted that the tentens equation is an approximation, and other versions of the equation have been proposed and may be used in embodiments of the present invention.

The heat capacity relates energy to mass, and the air leakage rate gives the volume of air leakage rather than mass. Therefore, it is necessary to consider the density of air. Since water molecules are lighter than air, the density decreases as the humidity increases. This relationship can be expressed as

Where T is the temperature in Kelvin, p_dIs the partial pressure of dry air, M, defined above_dIs the molar mass of dry air, M_wIs the molar mass of water vapour, p_wIs the partial pressure of water vapor and R is the specific gas constant of dry air.

In equations (2) to (6), the parameters used are parameters for outside air. Whether the air leak enters the building or leaves the building, and whether the outside air is warmer or colder than the air inside the building, it is the outside air that is delivered to the interior of the building by the air leak or ventilation system that needs to be heated or cooled to the temperature of the indoor air. Therefore, the heat capacity of the outside air is relevant to calculate the energy loss caused by the leakage.

Now the energy factor K can be adjusted_EIs defined as

Where the heat capacity and density are derived from equations (2) and (6), respectively, 1/3.6 is a conversion of kJ to Wh, and η is the efficiency of the heating or cooling process. The latter ensures that the calculated energy loss is given by how much energy is required to make up for the loss caused by the air leak, and not just the energy content of the air leak. The power (in watts) required to compensate for this can be expressed as

E＝q_pr·ΔT·K_E (8)

As can be seen from the above equation, the energy loss can be found based on measurements of internal and external pressures, external relative humidity and external and internal temperatures. Except for the air leakage rate q_prAll other parameters, except those determined as described above, are derived from these parameters or they are known constants. These measurements and calculations provide an estimate of the power required to compensate for energy loss caused by air leaking through the building envelope.

The temperature difference between the inside and the outside may be provided by the sensor controller 2 based on input from a temperature sensor T connected to the sensor controller 2. Similarly, the differential pressure may be provided by the sensor controller 2 based on input from the differential pressure measurement device 1. The absolute air pressure may be provided by external and internal air pressure sensors B, respectively. Alternatively, only one air pressure sensor B is provided inside or outside, and the absolute air pressure of the other side is calculated from the measured absolute pressure and the differential pressure measured by the differential pressure measuring device 1. The humidity outside and inside the building envelope is measured by a humidity sensor H. The computer system 20 may receive sensor data from the sensor controller 2 and the differential pressure measurement device 1 via the wireless access point 21 and calculate the air leakage rate per hour using the above equation.

The system may be further configured to calculate how much water the air outside and inside the building contains. Based on this, the system may be further configured to calculate how much water air leaking through the enclosure contains and how much water the air will lose to condense if it leaks from the warmer side to the cooler side. If cool air or warm air sufficiently dry leaks through the wall, the leaking air does not cause any condensation. However, if warm moist air leaks into the cold air, condensation may result, depending on the dew point of the warm moist air and the temperature of the cold air. Condensation typically occurs if hot humid air is drawn into a cold building in the summer or leaks into dry, cold outdoor air in the winter.

How much water will be deposited by condensation depends on several factors. It will be appreciated that if the hot humid air is cooled only to a temperature above the dew point, no condensation will occur. And, of course, if the cool air leaks to the warmer side, no condensation occurs.

However, by calculating the absolute humidity of the outside and inside air and calculating the air leakage rate using equation (1), the upper threshold for water condensation can be determined. The absolute humidity in kilograms per cubic meter can be calculated as

Wherein p is_wAnd p_satIs the partial vapor pressure and the saturated vapor pressure, R being as already described above_wIs a specific gas constant for water vapor, about 461.5J/kg K, and Φ is the relative humidity. As described above, p can be obtained from Tetens equation (5)_satAnd measuring pressure, relative humidity and temperature. Equation (7) can be used to calculate the absolute humidity of the outside and inside air. If the difference is positive (i.e., if the hot humid air leaks into the cold dry air), the absolute humidity difference between the outside and inside air is multiplied byAn upper threshold for condensation is provided at the air leak rate.

Limiting rate of condensation q_pr·|AH_out-AH_in| (10)

The condensation rate limit represents an upper limit on the amount of water that may be deposited as condensation when the hot humid air is cooled to the same temperature as the cold dry air on the other side of the enclosure.

Those skilled in the art will appreciate that if air moves from the wet side of the enclosure to the cooler side of the enclosure, water may be deposited as condensate. As previously mentioned, if the temperature of the cooler air is above the dew point of the hot humid air, the excess humidity will simply be absorbed by the dry, cool air. If the temperature of the cool air is below the dew point of the warmer, moist air, the leaked air will lose excess humidity and form condensation when cooled to the temperature of the dry, cool air.

Those skilled in the art will recognize that this equation does not take into account additional factors such as dew point, ventilation, heat recovery, or other aspects. More accurate calculations can be made, for example by using a Mollier diagram. Equation (10) also does not describe where condensation occurs. However, if the leaking air moves relatively slowly through the building envelope, its temperature drops significantly as it passes through the wall and condensation is likely to occur inside the wall, causing structural damage, mold, or other problems.

To eliminate or reduce this risk, one aspect of the invention includes using the results of the measurements and calculations to control the ventilation system of the building to prevent or at least reduce air leakage through the building envelope from the warmer, wet side to the cooler, dry side.

In some embodiments, the present invention simply ensures that the air pressure inside the building is equal to or slightly higher than the air pressure outside the building if the inside air is cooler and drier than the outside air, and conversely, that the inside air pressure is equal to or slightly lower than the outside air pressure if the inside air is hotter and more humid than the outside air. This will ensure that air leaking through the building envelope is cooler and drier than it encounters on the other side of the envelope. Such control of the internal air pressure can be achieved by controlling the speeds of the intake fan and the exhaust fan using the fan control 4.

As explained with reference to fig. 1, the stack effect causes the internal air pressure to vary so that air can pass through the envelope of the lower part of the building in one way and the envelope of the upper part of the building in another way. The air pressure difference may also vary for other reasons, such as wind 15, different temperatures in different parts of the building, variations in the amount of air pumped into or out of the building in different parts of the building, the degree to which air is free to flow between different parts of the building, etc.

Additional considerations are added to the situation just described. Since there should be a slightly lower air pressure on the hot and humid side of the enclosure in all parts of the building, some parts of the building may experience a higher differential than is required for that part of the building. To ensure that air flows consistently from the cooler side to the warmer side, at one or more locations where the pressure differential is measured, how high the pressure differential needs to be at all, possibly depending on the height of the building, the air leakage coefficient, the effective leakage area, the wind, and other variables. Therefore, it may be necessary to calibrate the minimum air pressure difference based on measurements or theoretical calculations specific to the characteristics of the building in which the invention is installed.

The air pressure differential between the interior and exterior of the enclosure need not be great to ensure that air leaks in the desired direction. A minimum value of the pressure potential difference across the building will result in a net transfer of air from the side with the highest pressure until the pressures on the two sides are balanced. One factor that affects how much potential difference is needed is the resistance in the airflow chamber path. The composition and complexity of the wall assembly, as well as the location and shape of the channels that move the air, will cause drag and thus increase the potential difference required to ensure that the air moves through the wall in one direction. Furthermore, wind and stack effects can cause pressure differences and fluctuations on different sides and on different floors of the building. It is therefore necessary to ensure that the required pressure difference is obtained anywhere, not just at the location of the pressure measuring device 1. Thus, while a pressure differential of only 0.1Pa may be sufficient, it may be necessary to increase the differential to, for example, 1Pa or more to ensure that the required minimum pressure differential is achieved throughout the building. The present invention is not limited to any particular pressure differential. Rather, the required differential pressure may be adjustable, such that the configuration of a particular installation may be based on the location of the differential pressure measurement device 1, the number of floors, how air moves between the floors and the rooms inside the building (depending on fans, ventilation shafts, doors, and open corridors), wind, and other factors that may be relevant to a particular situation.

Those skilled in the art will recognize that if the dew point of the hot wet side is lower than the temperature of the cold side, then the direction of air leakage may not be important, at least not to avoid condensation, and preventing energy loss may still be the highest priority. However, other considerations may be taken into account. For example, if the atmosphere within the enclosure is controlled in terms of pollution, dust or other elements that may be present in the outside air but removed by the ventilation system before the air is introduced into the building, it may be necessary to ensure that the air pressure inside the enclosure is higher than outside.

Referring now to fig. 4, in a first view fig. 4a shows a building with multiple stories. In this example, each floor is provided with a differential pressure measuring device 1 and a sensor controller 2. Each sensor controller 2 may be connected to one or more indoor and/or outdoor sensors. It may not be necessary to provide a complete set of sensors for each sensor controller 2. To avoid unnecessarily cluttering the drawings, the sensor T, B, H is not included in the drawings. It can be assumed that they are connected to various sensor controllers 2.

The air pressure varies with altitude. This difference is the same inside and outside the building if everything else is equal. However, due to the above-mentioned stacking effect, the pressure difference will vary from floor to floor, and so will the resulting infiltration 17 and the infiltration 18. Since air moves between floors through elevator shafts, stairwells, and other openings, it may not be practical to determine the air leakage rate of individual floors. As an approximation, it can be assumed that the air leakage rate is proportional to the envelope area of a particular floor. For example, if the entire enclosure has a regular shape and the floor and roof can be ignored, then the air leakage rate per floor can be assumed to be 1/6 of the total air leakage rate for a six-story building. If the shape, size or characteristics of the building envelope vary from floor to floor, for example, depending on floor height, number and size of windows or vents, doors (primarily in the basement), irregular shapes, uses, etc., adjustments may be required. Taking all these factors into account, and by measuring or estimating the air pressure difference at each floor, the air leakage and thus the energy loss at each floor can be estimated.

In the second view of fig. 4b, a simplified plan view of the building is shown from above. In this particular example, the floor comprises a plurality of rooms 20 connected by interior doors 21 and doorways 22. Other openings, such as vents, channels, etc., may also be present. The more complex the subdivision of the floor and the way air flows between them, the more complex the measurements and calculations become. In the example shown, the sensor controller 2 is present in two rooms, while one room is without any sensors. This means that it becomes necessary to estimate the conditions in the room without sensors. This does not hinder the solution obtained by the invention, but the accuracy of the results obtained may be reduced whenever an estimation has to be substituted for an accurate measurement. As a first approximation, it can be assumed that the air pressure of the whole floor is equal, since air will flow from the higher pressure room to the lower pressure room until equilibrium is established. If there are multiple air pressure sensors and different results are given to different rooms, the air pressure in the room without sensors can be approximated based on the manner in which the sensors are connected to other rooms and the measured pressures in those other rooms.

Similar to the description above regarding individual floors, the air leakage rate for an individual room may be based on the proportion of the partial enclosure of the room in the entire enclosure of the building. For example, if the building envelope is 2500m²And the outer wall of the specific room is 10m²The air leakage rate of the room as a function of the pressure difference can be assumed to be 1/250 of the air leakage rate of the entire building^th。

Not only the air pressure may vary throughout the building. The temperature may also be different in different rooms. For example, if the room is unoccupied, the temperature of the hotel room may be heated (or cooled) less to conserve energy. If this is the case, the calculated energy loss may be based on the average temperature of the entire building or on the calculation of the individual floors and/or rooms based on a proportional portion of the enclosure that may be associated with that floor or room, as well as the measured temperature and the measured or estimated air pressure differential.

Finally, the humidity of the entire building may also vary. For example, humidity may depend on the extent to which air is transported through the enclosure (e.g., through the main entrance of the building), and the usage of different parts of the building. For example, in a kitchen, bathroom or natatorium, even in a meeting hall during an activity, the humidity may be much higher than in other parts of the building. Again, the extent to which this is taken into account during the calculation of the energy loss and the dew point depends on the availability of the sensors and the accuracy of the estimates that can be made without the sensors.

As described above, in various embodiments, the system according to the present invention may be used to measure the current conditions within and around a building and calculate the energy loss through the enclosure due to air leakage and the rate of condensation of air transported through the enclosure.

In some embodiments of the invention, the results from the monitoring system may be used to control a ventilation system of a building. This is done to optimize ventilation according to one or more of the following criteria:

it is desirable to achieve an air pressure inside the enclosure equal to the air pressure outside the enclosure to avoid air leakage through the building enclosure-i.e. as much air as possible delivered into the building or out of the building should be delivered through the ventilation system.

It is desirable to avoid cooling down the warm humid air so that it meets its dew point within the structural elements (walls, etc.) making up the enclosure or on other surfaces inside the enclosure to avoid condensation that may lead to damage.

It is not desirable to use more resources on the ventilation system than actually gained in terms of power and load-for example, it would be counterproductive if more energy was spent in obtaining pressure equality, rather than energy lost to air leakage without obtaining pressure equality.

Hereinafter, a method of controlling a ventilation system using an embodiment of the present invention will be described. These methods will be described based on the assumption that the air pressure, temperature and humidity inside the entire enclosure are the same. To the extent that air pressure differentials, temperatures and humidity vary in different parts of a building, the considerations discussed above regarding sensor availability, accuracy of estimation and the proportional size of the enclosures that may be associated with different rooms or floors of the building become relevant.

Returning now to FIG. 3, in an embodiment of the present invention in which the system is configured to not only monitor selected variables, but also to control a ventilation or HVAC system based on the results of the monitoring, the computer system 20 may be configured to control the fan controller 4. It is also possible that the heat exchanger 6 and other controllable parts of the ventilation system, such as the ventilation opening, and the air dryer or humidifier. In larger buildings, any number of fans, heat exchangers and other HVAC components may be controlled, but for simplicity of explanation, this example includes one fan and one heat exchanger. This assumption is made without loss of generality, but as the system becomes more complex, the considerations outlined above become relevant.

The fan controller 4 controls the speed of the fans in the fan assembly 5 to control the amount of air pumped into or out of the building (or into or out of the building if both an intake fan and an exhaust fan are present) per unit time. Pumping air into the building increases the pressure relative to the outdoor pressure, while pumping air out of the building decreases the indoor pressure. Being able to control the area of the open enclosure (e.g. by opening or closing vents) may have additional effects. Controlling the air fan controller 4 based on the measured pressure difference may be used to achieve the first goal, i.e. to achieve the same indoor air pressure as outdoor. If a building is composed of multiple floors and/or multiple rooms with limited air passages between them, it may be necessary to control the fans in different ways in different parts of the building. In light of the above considerations, the various fans may be controlled based on measurements or estimates of variables applicable to the area of the building in which the fan is located, for example. This adds complexity to the system but does not change the problem itself.

Fig. 5 is a flow chart illustrating a method for determining energy loss caused by air leakage using a system according to the present invention. The method starts in a first step 501 in which a measured differential pressure is received from a differential pressure measurement device 1. In a subsequent step 502, the air leakage rate is calculated, for example, by using the measured differential pressure and the air leakage coefficient and air flow index previously obtained in equation (1).

The output from step 502 is a calculated volume of air leaking through the enclosure per unit time.

In step 503, the temperature and humidity on each side of the building envelope are measured. It should be understood that in various embodiments of the present invention, these measurements are made continuously or regularly, and the method uses the last received value. The method does not require that the steps be performed in a particular order, as long as the required measurements are available at the time the calculations are made.

Based on the obtained measurements, the energy loss may be calculated in step 504. The energy loss can be calculated using equation (8). As described above, equation (8) uses the air leakage amount calculated by equation (1), the difference between the measured indoor and outdoor temperatures, and the energy factor K in equation (7)_E. The energy factor K can be adjusted for the efficiency of the heating or cooling process_ETo determine the energy required to make up for the losses.

In step 505, moisture transported out of or into the building due to air leakage may be determined or estimated. The estimation may be based on equations (9) and (10), whereby an estimate of the absolute moisture content of the inside and outside air is calculated and the difference between the two is multiplied by the air leakage rate. Another way to describe this is to calculate an estimate of the absolute moisture content of the air delivered out of (or into) the building per unit time (e.g., per hour) due to the air leak, calculate a corresponding estimate of the absolute moisture content of the air delivered into (or out of) the building that compensates for the air leak, and the net moisture delivered into or out of the building is the difference between the two.

This moisture transport represents moisture that may be trapped within the building walls due to condensation if air leaks from the wet side of the enclosure to the dry side.

Fig. 6 is a flow chart of a method in which a system according to the present invention is used to control a ventilation system to reduce energy loss from air leakage.

In a first step 601, a measured differential pressure is received from the differential pressure measurement device 1. In step 602, measurements of indoor and outdoor temperatures and relative air humidity are received. These steps need not be performed in any particular order, and any one or more of the received values may be updated at any time. Outdoor measurements may be received from sensors that are part of the system, but alternatively they may be received from a provider such as a weather service.

In some embodiments, the dew point on the hottest side of the enclosure is calculated in step 603. Only the dew point of the hottest side needs to be determined since the temperature from the hottest side of the cooled air to the coldest side may cause condensation. The opposite is not true because air that is warmer in temperature from the coldest side to the hottest side does not cause condensation.

The dew point may be measured, or calculated, by a hygrometer. Calculation of the dew point is quite complex but is well known in the art. One well-known approximation is the Magnus formula

Wherein, T_cMeasured temperature in degrees celsius, Φ is relative humidity, b is 18.678, c is 257.14 ℃.Equation (11) may be replaced with a more complete formula or other approximation.

If the dew point of the hottest side of the enclosure is lower than the temperature of the coldest side, the air pressure does not have to be controlled to avoid condensation. This is determined in step 604. If it is determined that this is the case, the process proceeds to step 605 where the ventilation system is controlled to adjust the pressure differential toward zero. This may be achieved by controlling the fan controller 4 such that if the internal pressure is lower than the external pressure, more air is pumped into the building (or less air is bled from the building) whereas if the internal pressure is higher, less air is pumped into the building (or more air is bled from the building).

Such control may be achieved by adjusting the speed of the intake and exhaust fans, or by controlling the vents.

If it is determined in step 604 that the temperature on the coldest side is below the dew point on the hottest side, it may be desirable to ensure that air does not leak from the hottest side to the coldest side. This may be achieved by controlling the ventilation system such that the pressure on the coldest side is higher than the pressure on the hottest side by a predetermined threshold. In this way, any air leaking through the enclosure will be cooler than it encounters on the other side, and since the leaking air is not cooled, no condensation will occur.

The size of this threshold does not have to be particularly large. In many cases, a pressure difference of 0.1Pa may be sufficient. To increase the safety margin, the value may be increased to 1 Pa. Generally, the characteristics of buildings can vary greatly, particularly if the building includes multiple floors and zones on the same floor, with limited air flow between them and differences in air temperature and humidity. For more complex buildings, the air pressure threshold should be obtained in all parts of the building, which may require a higher threshold where the differential pressure measuring device 1 is located. General rules cannot be specified for this. Rather, this would be a case-by-case design requirement.

It should be noted that it is not necessarily absolute to avoid condensation by ensuring that cooler air leaks towards the hotter side. Regardless of the manner in which air leakage occurs, cooler air meets hotter air, and locally some air is heated and some air is cooled. This means that even if cooler air leaks, there may be some condensation from the warmer air it encounters. However, since the volume of air that leaks is much less than the volume of air that it encounters, the cooler air that leaks absorbs and heats the warmer air that it encounters to a much greater extent than if the warm air that leaks encountered the cooler air. However, in some embodiments, it may be considered advantageous to ensure that air leakage always flows from the interior of the enclosure to avoid cold air leakage to cold surfaces around locations in the building. Thus, in some installations, it is consistent with the present invention to allow or force air to leak from the hotter side to the colder side of the enclosure.

Some embodiments of the invention do not include calculation of the dew point and the system is simply configured to adjust the pressure differential toward zero. In other embodiments, the dew point calculation is omitted, but a threshold is enforced so that there is always some air leakage from the cooler to the warmer side or from a predetermined side (inside or outside) to the other side.

In this disclosure, the term ventilation system has been used to refer to systems that include an intake and/or exhaust fan. This does not mean that the system covered by the term does not comprise additional functions, such as heating, cooling, humidification or dehumidification, etc. Thus, the term is intended to include air conditioning and HVAC systems. In addition to regulating the air pressure differential by controlling the fan, the present invention may be modified to control ventilation, heating, heat exchangers, humidifiers, and dehumidifiers to regulate the indoor climate in a manner that reduces the chance of energy loss or condensation within a building or wall.