WO2009103963A1

WO2009103963A1 - An integrated ventilation and heating system and a method of operating the same

Info

Publication number: WO2009103963A1
Application number: PCT/GB2009/000434
Authority: WO
Inventors: Andrew W. Woods
Original assignee: E-Stack Ltd.
Priority date: 2008-02-18
Filing date: 2009-02-18
Publication date: 2009-08-27
Also published as: GB2458440A; GB2458440B; GB0802937D0

Abstract

An integrated ventilation and heating system for a room, building or the like comprises a ventilation stack having an interior space, a first opening which in use provides fluid communication between the interior space and the room, building or the like to be ventilated, and a second opening which in use provides fluid communication between the interior space and ambient atmosphere, the interior space in use providing a mixing space for air entering the stack from the room and air entering the stack from the ambient atmosphere. A heating control device controls the operation of a heating apparatus that provides heat to the room, building or the like. A system controller controls both the operation of the heating control device and the size of at least the second opening according to a pre-determined room condition.

Description

AN INTEGRATED VENTILATION AND HEATING SYSTEM AND A METHOD OF OPERATING THE SAME

The present invention relates to an integrated ventilation and heating system for a room, building or the like, and to a method of operating the same.

In cold conditions, a building loses heat to the exterior through ventilation and through losses through the walls/windows of the building. Occupants within the building produce heat through their activity, including for example computer usage and lighting. In terms of an energy balance, any mismatch between the heat produced by such activity and the heat lost to the exterior determines the heating requirement for the building or room.

Furthermore, air that is input into the building for ventilation purposes normally requires pre-heating to raise the temperature of the air to a comfortable temperature for the occupants of the building. This pre-heating requirement can be achieved with the use of a mechanical heating system through which the incoming air passes prior to reaching the occupants in the room or building, or it may alternatively be achieved through mixing the incoming ventilation air with warmer air that has been extracted from the room or building, the mixing taking place within a mixing chamber. According to the latter solution, a ventilation stack mounted on the roof of a building may include a controlled low energy mixing chamber located between the room or building to be ventilated and the exterior atmosphere. Air flow into the mixing chamber from the room or building is regulated by opening and closing a variable damper, controlled according to measurements taken at temperature and CO₂ sensors within the room. In this manner, pre-mixing of incoming ventilation air with warm air from the room is managed so as to provide ventilation air to the room at a comfortable temperature. This stack ventilation system has the advantage of providing pre- warmed ventilation air to the room or building without the need for electrical or other form of power to pre-heat the air, thus making the system cheaper than mechanical ventilation systems and using less energy than such systems.

However, it is desirable to make the building or room even more energy efficient for both environmental and cost reasons. The present invention seems to address these requirements at least to an extent.

According to a first aspect of the present invention, there is provided an integrated ventilation and heating system for a room, building or the like, the system comprising a ventilation stack having an interior space, a first opening which in use provides fluid communication between the interior space and the room, building or the like to be ventilated, and a second opening which in use provides fluid communication between the interior space and ambient atmosphere, the interior space in use providing a mixing space for air entering the stack from the room and air entering the stack from the ambient atmosphere, a heating control device for controlling the operation of a heating apparatus that provides heat to the room, building or the like; and a system controller for controlling both the operation of the heating control device and the size of at least the second opening according to a measured room condition.

An advantage of controlling the heating system and the ventilation system using a common system controller is that the heating need only be used if the conditions in the room or building require it, that is when the interior heat gains generated by human and machine activity are insufficient to match the heat losses through the walls and windows. At all other times the heating can remain either off or on at a minimum setting. By making use of the interdependency of the heating and ventilation requirements, the system results in a more energy efficient building or room than is the case when using the ventilation stack system alone.

According to a second aspect of the invention, there is provided a method of operating an integrated ventilation and heating system, the system comprising a ventilation stack having an interior space, a first opening which in use provides fluid communication between the interior space and the room, building or the like to be ventilated, and a second opening which in use provides fluid communication between the interior space and ambient atmosphere, the interior space in use providing a mixing space for air entering the stack from the room and air entering the stack from the ambient atmosphere, and a heating control device for controlling the provision of heat to the room, building or the like, the method comprising the step of measuring a room condition and controlling both the size of the second opening and the operation of the heating control device based upon the measured room condition.

The step of measuring the room condition may comprise obtaining a temperature measurement of the ambient air, obtaining a second temperature measurement inside the room, building or the like, and the step of controlling both the size of the second opening and the operation of the heating control device is based upon the first and second temperature readings.

The method may further comprise the step of measuring a CO₂ concentration inside the room, building or the like, and controlling the size of the second opening and the operation of the heating control device based upon the CO₂ concentration measurement. Preferably, the size of the second opening is kept to a minimum whilst the heating apparatus is operating to emit heat, unless the CO₂ measurement inside the room, building or the like exceeds a per- determined threshold. The heating apparatus may be switched on to emit heat only if the second temperature measurement is below a pre-determined threshold. The size of the second opening maybe increased only if the CO₂ measurement exceeds a pre-determined CO₂ threshold and/or the second temperature measurement exceeds a pre-determined temperature threshold. In this manner, the system controller can be configured to continually adjust the ventilation and heating settings to provide a dynamic control of both systems to minimise energy usage whilst maintaining comfortable conditions within the room or building.

The integrated ventilation and heating system may be installed in a room, building or the like. The installation may include at least a temperature sensor and a CO₂ sensor inside the room or building.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a schematic view of a first embodiment of an integrated ventilation and heating system according to the invention;

Figure 2 shows a schematic view of a cross-section of the ventilation stack of Figure 1; and

Figure 3 shows a schematic view of a second embodiment of an integrated ventilation and heating system according to the invention.

Referring to Figure 1, a room or building 10 has a single ventilation stack 20 mounted at the top of the room or building. The stack 20 has a first lower opening 40 at a ceiling of the room or building, the opening 40 leading into and providing fluid communication with an interior space 41. The opening 40 comprises a grille in the present embodiment, although in an alternative embodiment could comprise a valve member for selectively varying the size of the opening.

A valve member 42 is located at an upper region of the interior space 41 for selectively varying the size of a second opening 43 at the upper part of the interior space 41. The term "size", can include a single dimensional quantity such as length or width of the opening, or it could be a two-dimensional area. In the present embodiment, the valve member comprises a multi-blade damper that is controllable by an electric stepper motor (not shown), but other devices, such as a fluid thermostat (not shown) directly controlling the valve member could be provided. In an alternative embodiment, the valve member 42 may be a slide valve or any other suitable opening-controller, including an iris-type diaphragm.

Above the valve member 42, the stack 20 comprises an internal shaft or stack 50 that is surrounded by an external annular shaft or stack 60. The internal shaft 50 extends towards the uppermost part of the stack 20 and culminates in a roof termination 55. At the roof termination, the stack includes at least one opening 70 into which, in the present embodiment, cool ventilation air may flow in order to enter the ventilation stack. The outer annular shaft 60 also extends upwards towards the uppermost part of the ventilation stack 20 and terminates with at least one opening 80 via which, in the present embodiment, upflowing air may exit the stack 20.

Within the interior space 41, upper and lower fans 45a and 45b are provided, the fan 45a being located immediately beneath the valve member 42, whilst the lower fan 45b is located immediately above the grille member 40. The lower fan 45b is surrounded by a second internal shaft 46. In use of the ventilation stack 20, the fans 45a, 45b are contra-rotated in the present embodiment to assist drawing of the air downwards into the internal shaft 50 from the atmosphere or to draw air upwards into the annular shaft 60 from the room or building 10.

However, in an alternative embodiment in which the fans 45a, 45b are contra- rotated in an opposite manner to that of the present embodiment, the stack can be operated such that inflow is through the outer annular shaft 60 whilst the outflow from the room or building 10 is through the internal shaft 50.

In an embodiment, the roof termination 55 may house a solar photo voltaic cell 170 that can be used to drive the fans 45a, 45b.

A temperature sensor 90 is located in the inner shaft 50 adjacent one of the openings 70 in order to measure the ambient air temperature outside of the room or building.

The room or building 10 has installed therein a heating apparatus, such as a hot water system having one or more radiators 100. The radiator 100 emits heat into the room when the heating apparatus is switched on. Operation of the radiator is controlled at a heating control device 110, which in the present embodiment is a control valve such as an electronic control valve . Adjustment of the control valve 110 determines whether the radiator is switched on and if switched on, the level of heat emitted into the room from the radiator.

The room further includes a carbon dioxide (CO₂) sensor 120 and a temperature sensor 130. Each of the sensors, together with temperature sensor 90, provides an input to a control algorithm run in a system controller 150. The room will also include one or more windows or doors, which provide low level ventilation into the room when open or ajar. In the illustrated embodiment, a window 140 is shown.

The ventilation stack 20 operates as described below and with reference in particular to Figures 1 and 2. When the room or building 10 is occupied with people or computers or other heat sources, the room air warms up and naturally rises into an upper region 25 of the room or building. The warm air passes through opening 40 into the interior space 41 of the stack 20. If it is desired to draw a higher flow rate of warm air through the opening 40, the fan 45b may be switched on. Meanwhile, cool ventilation air from outside of the room or building 10 enters the stack 20 via opening 70, and sinks downwards through the inner shaft 50 and through the valve member 42 into the interior space 41 at a controlled flow rate depending on the size of the opening 43. The fan 45a may be utilised to assist in drawing a higher flow rate of ventilation air through the inner shaft 50 if necessary.

Once inside the interior space 41, the cool ventilation air is able to mix with the warmer room air such that a degree of natural heat exchange takes place between the two streams of air. The ventilation air becomes warmer whilst the room air becomes cooler. The warmed ventilation air then passes through the opening 40 and into the room or building 10 where it falls to occupant level at a temperature that is comfortable to the occupants.

The ventilation stack system 20, window 140 and the heating apparatus 100 are controlled by the system controller 150, shown schematically in Figure 1. The controller comprises an intelligent control circuit that effects operation of the ventilation system 20 and low level window ventilator 140 as well as operation of the heating apparatus 100 via the control valve 110. The objective of the control logic is to operate the ventilation stack at the minimum necessary to remove excess heat from the room and to maintain air quality whilst operating the heating apparatus only when necessary and at the minimum to maintain the room at a comfortable temperature for the occupants. In general, two operating regimes arise; a cold regime and a warm regime In the cold regime, the ventilation system requires hot air emitted from the heating apparatus in order to pre-warm the ventilation air, and the ventilation is run at a minimum. In the warm mode, the integrated system requires no heating and the ventilation is run at a rate above minimum to vent the excess heat from the building. The controller 150 regularly receives data from the temperature sensors 90 and 130 and from the CO₂ sensor 120, which it uses as input to provide a dynamic control of the valve member 42, the fans 45 a and 45b, the window 140 and the heating control device 110 in both the cold and warm regimes.

As the external temperature increases beyond the critical value at which no heating is required, the net ventilation rate is increased by the system, until reaching a threshold of e.g. four or five times the minimum ventilation, in order to vent the heat from the room or building 10. If the external temperature measured at temperature sensor 90 is below a desired interior temperature, the ventilation is run at a maximum rate whilst maintaining consistency with the thermal comfort of occupants within the room or building 10. If the external temperature measured by sensor 90 reads above the desired interior temperature, then the ventilation is run at the minimum rate to ensure that the incoming hot air through the ventilation stack 20 places only a minimum additional burden on the integrated system.

A specific example of an algorithm that may be used to operate the integrated ventilation and heating system is described below. It will be apparent to the skilled person that this is merely an illustrative example and that variations in the algorithm can occur. In particular, the choice of design temperature and the various threshold temperatures and concentration of carbon dioxide may vary from application to application.

(0) External air temperature (T_e) is measured at temperature sensor 90. • If T_e < 18°C, continue to step (i). Otherwise, go to step (a).

(1) Check interior room temperature (Tj) at sensor 120 and check CO₂ concentration at sensor 130.

- if Tj < 19°C, close low level ventilator 140 and wait five minutes.

- if CO₂ > 800pprn, open valve member 42 to a low setting.

(ii) Check interior room temperature (Tj) at sensor 120.

- if Ti < 19°C, turn heating apparatus 100 on at heating control device 110. If heating apparatus 100 is already on, turn up heat setting 1 unit at heating control device 110. Wait five minutes.

- if 19°C < Ti > 24⁰C and heating is on, turn off heating apparatus 100 at heating control device 110. Maintain valve member 42 at current setting.

- if CO₂ concentration is rising and > 800ppm, open valve member 42 to next setting. Wait five minutes.

(iii) Check interior room temperature (T₁) at sensor 120. - if heating is off and Ti > 24⁰C, open valve member 42 further to increase ventilation rate.

- Otherwise, wait five minutes and go back to (0).

(a) IfT₆ > IS⁰C, continue to step (b).

(b) Check interior room temperature (Ti) at sensor 120 and check CO₂ concentration at sensor 130.

• If 19°C < T₁ < 24°C and CO₂ < 800ppm, close low level ventilator 140, close valve member 42 and if heating apparatus 100 is on, turn it off at heating control device 110.

• if T₁ > 24⁰C or CO₂ > 800pρm,

open low level ventilator 140, open valve member 42 to next setting to allow upflow of room air into interior space 41. Wait five minutes.

(c) check interior room temperature (Tj) at sensor 120 and check CO₂ concentration at sensor 130.

• if T₁ > 24⁰C or CO₂ > 800ppm, open valve member 42 to next setting or, if valve member 42 is fully open, switch fans 45a,45b on to low setting or increase fan setting one level. Wait five minutes. • if Ti < 19°C, close valve member 42 and switch off fans 45a,45b.

(d) Return to (0).

The skilled person in the art will appreciate that there are many ways of programming such an algorithm, and that needs are conventional in the art and will not be described here.

In a modification of the system, the ventilation stack 20 may also include a stack temperature sensor 160 shown schematically in Figure 2. The stack temperature sensor 160 may form a further input into the control algorithm. For example, if the temperature measured at the stack temperature 160 is found to be less than 19°C, the speed of fan 45b can be increased to encourage the removal of warm air from the room or building 10 into the ventilation stack 20.

The heating apparatus 100 may be gas or electrically powered or may be powered, in an embodiment, using solar hot water tubes or it may be powered by solar heated phase change material, such as encapsulated wax particles, in suspension, to further reduce energy load on the integrated system. Electricity for the entire integrated system may be provided by the photo voltaic cell 140 in an embodiment.

It will be apparent to the skilled person that in each of the inner shaft 50 and the outer annular shaft 60 it is possible that two way flow may occur. However, when fans 45a and 45b are in operation and are contra-rotating, air flow will tend to flow upwards through annular shaft 60 and downward through inner shaft 50. If the fans 45a and 45b are operated in co-rotation, for instance in the warm mode, air will flow in one predominant direction, in this case to expel excess warm air out through the stack and into the ambient atmosphere.

In a further embodiment shown schematically in Figure 3, to be used in a building or room occupying a large space, two ventilation stacks 20' and 20" are provided at the top of the room or building 10'. The two stacks 20',20" are spaced apart from each other. In the embodiment shown, stack 20" operates as the stack of Figs. 1 and 2. The fans 45a", 45b" are counter-rotated so as to achieve mixing of the incoming ventilation air with the warmer room air inside the interior space 41". The fans may be operated at the same speed or at differing speeds to each other. When operating at the same speed, the flow rate of ventilation air drawn into the interior space will be approximately equal to the flow rate of air drawn in from the room 10 by fan 45b". However, if one of the fans is operated at a faster speed than the other, then the stack produces predominantly incoming ventilation air or predominantly outflowing warm room air. For example, if fan 45b" is operated at a faster speed than fan 45a", more warm room air drawn in by fan 45b" than cool ventilation air drawn in by fan 45 a". The net result will be to allow excess warm air from the room to be ventilated out of the stack 20". If fan 45a" is operated at a faster speed than is the fan 45b" then there will be a higher flow rate of incoming ventilation air entering the interior space than there will be warmer room air, resulting in a predominance of cool ventilation air entering the room from the stack. The stack 20' is operated as an "outflow" to pump excess warm room air out of the stack 20'. The stacks 20', 20" are controlled by the controller 150' according to the desired level of ventilation in the room and inputs from temperature and CO₂ sensors as before. This is achieved by co-rotating the fans 45a',45b' in an "upflow" mode by which room air is drawn upwards into the stack 20'. The direction of rotation of the fans 45a', 45b' and 45a", 45b" may be changed periodically in order to alternate the operating modes in each stack so as to provide an even ventilation into the room or building.

In each of the embodiments described above, the first and second openings are shown to be located at the top and bottom of the stack. However, one or both of the openings could be located on the side of the stack. The first and second openings need not be vertically displaced, and could be located at the same vertical level as each other. The stack or stacks may be mounted at locations other than the top of the building. The "internal" stack 50 and outer stack 60 need not be annular or co-axial. In an embodiment they may each be square or rectangular or other appropriate cross-sectional shape, and they may be located side-by-side, rather than co-axially.

The term "opening" will be understood by the skilled person to include an aperture or a conduit, the size of which is or may be variable to control flow rate therethrough. Where the valve members are single or multi-blade dampers, it will be understood that the size of the "opening" can be varied by opening or closing the single or multiple blades.

The desired room temperature depends upon the environment in which the system is operated, and in practice it may be higher or lower than the desired temperature in the embodiment above.

The integrated ventilation and heating system may be an integral part of the building design or it may be added later as a retro-fit.

Various modifications may be made to the embodiments described without departing from the scope of the invention as defined by the following claims.

Claims

1. An integrated ventilation and heating system for a room, building or the like, the system comprising a ventilation stack having an interior space, a first opening which in use provides fluid communication between the interior space and the room, building or the like to be ventilated, and a second opening which in use provides fluid communication between the interior space and ambient atmosphere, the interior space in use providing a mixing space for air entering the stack from the room and air entering the stack from the ambient atmosphere; a heating control device for controlling the operation of a heating apparatus that provides heat to the room, building or the like; and a system controller for controlling both the operation of the heating control device and the size of at least the second opening according to a pre-determined room condition.

2. An integrated ventilation and heating system as claimed in claim 1, in which the pre-determined room condition is measured by at least one sensor, the output of which provides an input to the system controller.

3. An integrated ventilation and heating system as claimed in claim 2 in which the sensor is a temperature sensor.

4. An integrated ventilation and heating system as claimed in claim 3, further comprising a CO₂ sensor.

5. An integrated ventilation and heating system as claimed in claim 1 in which the heating control device comprises a control valve.

6. An integrated ventilation and heating system as claimed in claim 1, further comprising an additional power source disposed inside the interior space to assist mixing of air in the interior space.

7. An integrated ventilation and heating system as claimed in claim 6 in which the additional power source is a fan.

8. An integrated ventilation and heating system as claimed in any preceding claim, further comprising a solar photovoltaic cell for providing power to the additional power source and/or the heating control device.

9. An integrated ventilation and heating system as claimed in any preceding claim, further comprising a low level ventilator in the room, building or the like to provide additional ventilation thereto.

10. An integrated ventilation and heating system as claimed in claim 5, in which the ventilation stack is configured to provide a pre-dominantly incoming flow of ventilation air into the room or building and in which the low level ventilator is configured to provide a pre-dominantly outflow of air from the room or building.

11. An integrated ventilation and heating system as claimed in any preceding claim in which the ventilation stack further comprises an inner stack, and an outer stack surrounding the inner stack, each of the inner stack and the outer stack having a first end that is in fluid communication with the interior space, and a second end located at the second opening.

12. An integrated ventilation and heating system as claimed in any preceding claim in which at least one further ventilation stack is provided in spaced relationship from the first ventilation stack.

13. A method of operating an integrated ventilation and heating system for a room, building or the like, the system comprising a ventilation stack having an interior space, a first opening which in use provides fluid communication between the interior space and the room, building or the like to be ventilated, and a second opening which in use provides fluid communication between the interior space and ambient atmosphere, the interior space in use providing a mixing space for air entering the stack from the room and air entering the stack from the ambient atmosphere, and a heating control device for controlling the provision of heat to the room, building or the like, the method comprising the the step of measuring a room condition and controlling both the size of the second opening and the operation of the heating control device based upon the measured room condition.

14. The method of claim 13, in which the step of measuring the room condition comprises obtaining a first temperature measurement of the ambient air, obtaining a second temperature measurement inside the room, building or the like, and controlling both the size of the second opening and the operation of the heating control device based upon the first and second temperature readings.

15. A method as claimed in claim 14, further comprising the step of measuring a CO₂ concentration inside the room, building or the like, and controlling the size of the second opening and the operation of the heating control device based upon the CO₂ concentration measurement.

16. A method as claimed in claim 15, wherein the size of the second opening is kept to a minimum whilst the heating apparatus is operating to emit heat, unless the CO2 measurement inside the room, building or the like exceeds a pre-determined threshold.

17. A method as claimed in any of claims 13 to 16 wherein the heating apparatus is switched on to emit heat only if the second temperature measurement is below a pre-determined threshold.

18. A method as claimed in claim 13 or claim 14 wherein the size of the second opening is increased only if the CO₂ measurement exceeds a predetermined CO₂ threshold and/or if the second temperature measurement exceeds a pre-determined temperature threshold.

19. A method as claimed in claim 13, in which the ventilation stack includes at least one fan and wherein the at least one fan is operated to produce pre-dominantly incoming flow from the ambient atmosphere through the ventilation stack or pre-dominantly outgoing flow to the ambient atmosphere through the ventilation stack.

20. A method as claimed in claim 13, in which the integrated ventilation and heating system further comprises a low level ventilator or second ventilation stack in the room, building or the like, and wherein the ventilation stack is operated to provide pre-dominantly incoming flow, the low level ventilator or second ventilation stack being operated to provide pre-dominantly outflow of air from the room, building or the like.

21. A method as claimed in claim 19, in which ventilation stack is partitioned between the interior space and the ambient atmosphere to provide separated first and second flow paths through the ventilation stack, the at least one fan comprising two fans, the method further comprising the step of operating the fans in contra-rotation so as to provide pre-dominantly incoming ventilation air through the first flow patch and pre-dominantly outflowing air through the second flow path or so as to provide pre-dominantly outflowing air through the first flow path and pre-dominantly inflowing air through the second flow path.

22. A room, building or the like, including an integrated ventilation and heating system as claimed in any of claims 1 to 12.

23. A room, building or the like as claimed in claim 19, further comprising a temperature sensor and a CO2 sensor disposed therein.

24. A room, building or the like, ventilated and heated according to the method of any of claims 13 to 18.