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review of residential ventilation technologies.

by:Trust&Deal Breeding Equipment     2020-02-26
This paper reviews current and potential ventilation technologies for residential buildings, with particular emphasis on climate and architecture in North America.
The main technologies reviewed include various mechanical systems, natural ventilation and passive ventilation.
Key parameters related to each system include operating costs, installation costs, ventilation rates, and heat recovery potential.
Related issues such as infiltration, piping systems, filtering options, noise and building issues are also studied in this paper.
This report describes the various systems currently available on the market to meet ASHRAE Standard 62. 2-
2004, low ventilation and Acceptable Indoor Air Quality
High-rise residential buildings.
While these systems generally fall into the category of supply, exhaust, or balance, the details of each system are driven by issues beyond the standard and discussed.
Some of these systems provide additional functionality (
Such as air distribution or pressure control).
The market will determine the direct value of these features, but ASHRAE may want to consider the relevant changes to the standard in the future.
The purpose of introducing ventilation is to provide fresh (
Or at least outdoors)
The air is comfortable and ensures a healthy indoor air quality by diluting contaminants.
Historically, people have ventilated buildings to provide source control for combustion products and bad odors (Sherman 2004a).
At present, there are various ventilation technologies available for ventilation in residential buildings, including mechanical systems and sustainable technologies.
Most of the existing housing stocks in the United States use the combination of penetration and window opening to ventilate, sometimes resulting in excessive ventilation, resulting in energy loss, sometimes resulting in insufficient ventilation and poor indoor air quality.
According to the work of Sherman and Dick Hoff (1998)
Sherman and Matterson (2002)
It has been shown that recent residential construction has created more stringent energy sources
Saving building envelopes that may lead to insufficient ventilation.
The penetration rate of these new homes is on average three to four times lower than that of existing housing stocks.
As a result, new homes often need to provide ventilation systems that meet current ventilation standards. (
Mike Williams and Sherman [2005]
And McKone Charman [2003]
These criteria and related factors were reviewed. )
According to ANSI/ASHRAE Standard 62. 2-
2004, low ventilation and Acceptable Indoor Air Quality
High-rise residential buildings published by the American Society of Heating, Refrigeration and Air
Air conditioning engineer (ASHRAE 2004)
Single, independent residential building needs to meet a whole
According to the number of bedrooms in the House, the number of occupants and the penetration credit (3 cfm per 100 [ft. sup. 2]plus 7.
5 cfm per additional occupant, which includes every 100 [2 cfm]ft. sup. 2]
Penetration allowance).
By means of mechanical systems or natural forces, there are many ways to achieve this standard.
But for some residents and homeowners, there is more ventilation in addition to meeting the standards.
For the comfort and health of the indoor environment, or to reduce the cost of energy, they may want to add some features.
According to the Journal of Family energy (
Kevin Rudd and Lstiburek 2001)
, A good ventilation system should * provide a controlled amount of uncontaminated outdoor air for comfort and dilution, * at least 15-
Annual Life, * acceptable for occupant operation (
Low noise, low cost)
And * does not affect the safety and durability of the house.
This paper will review mechanical and sustainable ventilation techniques and the factors that affect their effectiveness.
Mechanical Technology includes * continuous exhaust system, * intermittent exhaust system, * exhaust system with makeup air inlet, * Local exhaust and external air integrated in HVAC system, * continuous supply system, * intermittent supply with inlet on the return side of the HVAC system, * exhaust and supply combination (balanced)
No central mandatory system and * House
Air distribution system.
Sustainable Technologies, which are driven primarily by temperature difference and wind, are reviewed later in this paper, including * penetration with operable windows, * passive chimney ventilation, * solar chimneys, and hybrid systems.
The effects of infiltration and accompanying ventilation provided by operable windows were discussed.
Finally, various factors affecting ventilation effects are discussed, including cost and energy use, air cleaning and filtration, construction quality, control system and pipe system.
Mechanical whole
The house is ventilated with a variety of mechanical whole-
Indoor ventilation system including exhaust, supply and balance system.
Any of these items can be run continuously or intermittently, they can be single-port or multi-
Port, or can integrate the system into an existing HVAC system.
Mechanical ventilation strategy provides a more uniform ventilation rate than natural ventilation (Hekmat et al. 1986).
Compared to most other ventilation systems, well-designed mechanical systems provide good control of ventilation rates;
However, additional energy is required for the operating system. Holton et al. (1997)
Comparing the ventilation system of the new residential building, it is found that the penetration rate is from 0. 1 to 0.
Ach and 0 in Summer 07. 35 to 0.
Ach in winter.
Therefore, they recommend a mechanical ventilation system for modern houses.
The researchers studied various configurations of exhaust, supply and peaceful Hengtong wind system with overall ventilation and no overall ventilation
Indoor recycling of central heating and cooling air-
Handler fan, here are these.
Continuous exhaust system continuous whole-
House exhaust system by using single-point or multi-
The central fan that takes out the air from the building (Concannon 2002).
Supply air into the building housing through a gap or a provided vent (see Figure 1).
If the housing of the building is tight, negative pressure may be generated inside the building, resulting in reverse airflow from combustion (open flue)appliances.
Typically, these systems use a decompression damper to relieve the pressure imbalance.
Supply air to enter the building in an uncontrolled manner and possibly from a relatively unpopular area such as a garage, moldy basement (or crawlspaces)
Or a dusty attic (Barley 2002). Whole-
Residential exhaust systems may not be suitable in areas with high levels of external environmental pollutants.
In the case of radon, the researchers found that the exhaust system may actually increase the content of indoor pollutants (Bonnefous and others. 1994).
In a harsh climate, a very cold supply of air may produce airflow, while in a humid and humid climate area, exhaust-
Only the system can cause moisture damage to the building structure.
Can\'t add filter to exhaust wisely
Unless it is considered that the building housing is part of the filtration system, there is only a ventilation system.
Heat recovery can be increased in the exhaust system.
Passively, the building envelope itself can provide some heat recovery (
Walker and Sherman 2003b)
There are also some effects in removing ozone.
More actively, the exhaust heat pump can be used to recover the energy in the exhaust air flow.
Institute of Domestic Ventilation (HVI 2005)
A wide variety of fans are listed, which can meet the current ASHRAE ventilation rate criteria if properly installed.
However, several factors (
For example, the tightness of the building envelope, the size, the quality of the pipeline project and the placement of the pipeline, etc)
There will be a significant impact on whether the installed fan can provide indicated ventilation rate.
These fans can provide a ventilation rate of 50 cfm to 5000 cfm or more.
Most operating costs are caused by the energy of the air conditioner rather than the operating fan.
The HVI catalog lists only the energy usage of a small number of fans, with a typical power consumption of about 3. 5 cfm/W. Wray et al. (2000)
Find the exhaust from most angles
Only the mechanical ventilation system is the cheapest mechanical system. [
Figure 1 slightly]Single-
Point exhaust systemA single-
The point exhaust system is often an upgraded bathroom fan (e. g. , Figure 2).
The cost of construction and installation is the lowest in the mechanical system (Concannon 2002).
Only one fan is needed, and some simple pipes may be needed to drain the air out of the body.
In some cases, the fan can be installed on the outer wall and does not require a large number of pipes. Single-
The distribution of fresh air in the point ventilation system is uneven, especially in closed rooms (
Luther and lstiblek 2000).
In the evaluation of the five mechanical ventilation systems of Reardon and Shaw (1997)
Local exhaust found-
Strategy only (
It depends on the overall kitchen and bathroom fan
House ventilation)
Only provide better performance than penetration.
This simple system supplies bad air distribution. Standard 62. 2-
2004, however, there is no allocation requirement;
So this is not a problem for systems that meet the minimum standards, but it is still a consideration. Multi-
Point exhaust systemMulti-
The point exhaust system is better than the single exhaust system.
They improved the port exhaust system in the room-to-
Consistency throughout the room
The house is ventilated, but additional costs are required to install the plumbing works (Rudd 1999).
An exhaust fan is delivered to many rooms in the house and can be installed remotely to reduce noise levels.
In the comparison of ventilation systems, Reardon and Shaw (1997)
Found that if more than one episode
The point system is installed, the whole house, even the closed bedroom, and the air is evenly distributed.
The intermittent exhaust system is similar to the continuous exhaust system;
In general, it consists of a central fan used to remove stale air from the building, but it may also contain several fans in the high source area (i. e.
Bathroom and kitchen).
In this case, the fan (s)
Run only part of the time at a higher speed, and the size is suitable to provide the necessary ventilation.
The ventilation rate at the intermittent operation of the system must be greater than the ventilation rate at the continuous operation (Sherman 2004b).
There are several advantages to using an intermittent ventilation system.
When the outdoor air quality is poor, occupants can reduce the outdoor air volume entering the building.
Peak load problems may help reduce ventilation during certain periods of the day.
Cycle operations may also make more sense when ventilation systems are integrated with heating and cooling systems. [
Figure 2:
The occupant can control the fan when needed.
The downside here is that occupants control ventilation and have to rely on ventilation to know when ventilation is needed.
Occupants can choose not to operate the system (
For example, if there is noise from the fan)
This may lead to insufficient ventilation. (
If the system is standard 62. 2-2004-
Ventilation fans should meet sound requirements and noise should not be a substantial issue. )
Many systems use a timer to automatically run a fan for a certain period of time every day, so that occupants do not have to feel it when ventilation is needed.
However, when additional ventilation is required, occupants can usually control the switch to turn the fan on.
More complicated (and costly)
The control system including C [is available]O. sub. 2]
Sensors, occupant sensors, and humidity sensors. C[O. sub. 2]
Sensors and crew
The control system does not meet the current standard 62. 2-
2004 requirements, unless these functions are used to raise ventilation above the minimum rate required by the standard.
Our own experience shows that the cost of installation and operation is similar to that of a continuous exhaust system, but it may exceed them if complex control systems are installed.
As with the continuous exhaust system, most of the energy demand is to regulate the supply of air, not the operation of the fan.
Compared to the continuous exhaust system, if the intermittent system is used with the natural driving force to provide adequate ventilation while reducing the energy required to regulate the external air, it is possible to reduce the energy consumption.
For example, running a fan at night can reduce the cost of cooling.
In addition, the fan can be programmed to operate when the level of external contaminants is low, or to shut down the system when the external particulate matter or ozone water level is high. If time-of-
Use utility rates locally, at low-
Allows to reduce the cost cycle of even zero ventilation during high ventilationcost periods.
Exhaust system with makeup air intake another mechanical ventilation system uses exhaust fans, but controls the supply of air into the house by providing openings specifically for air supply (see Figure 3).
Rooms that require additional ventilation, such as a bathroom, can be equipped with a trickle outlet, air inlet, or blinds.
Similarly, it is impossible for this system to filter and supply air;
However, access points that supply air can be controlled, providing cleaner air by installing trickle vents in contaminated areas such as garages, moldy basements or dusty lofts.
In order to reach the standard 62, trickle is unnecessary. 2-
2004 per se, but may be required in exceptionally tight construction to reduce decompression and related issues.
Due to the compact structure, they are often used as part of a European system and ensure a separate air supply for habitable rooms.
Local exhaust integrated with external air in HVAC system this method is based on the above exhaust system, but an external air inlet is added to the return pipe system of air
Processing Unit of HVAC system.
According to the path (s)
In the case of minimal airflow resistance, this may use an existing plumbing system to extract air from various areas of the building.
Since existing pipe works will be used, very low marginal installation costs can be maintained.
This system can provide uniform ventilation throughout the house and can run intermittently or continuously.
When heating or cooling is not required, there will be additional operating costs for running a central fan, depending on the climate and system size.
The design of the exhaust system usually meets the standard 62. 2-
2004, unlike the central integrated gas supply system that not only provides ventilation, but also provides airflow distribution and can offset decompression ---
Both of these later attributes exceeded the minimum requirement of standard 62. 2-
2004 is often desirable.
In principle, the makeup air system can be designed to meet the standard of 62. 2-
2004, the exhaust system can be enhanced as a source control.
The continuous supply system allows occupants to control the location of the supplied air to maximize air quality and to allow occupants the option to filter and/or adjust the supplied air (
Construction Science Company).
The central fan delivers air to some or all of the rooms of the House, draining the dirty air through a leak in the building envelope.
This system creates positive pressure inside the building, which has both advantages and disadvantages.
The size of the pressure depends on the supply flow and the tightness of the envelope.
Positive pressure can prevent external contaminants from entering the building, but it can also force moisture
Fill the air through the building structure.
In a cold climate, wet air may condense on the walls of buildings, creating an environment for the growth of mold.
All kinds of research have considered the use
An indoor fan that provides night ventilation for cooling purposes (
Santamouris 2006).
In these systems, the air
Adjusting the load may be reduced by up to 56% depending on the occupant\'s thermal preference.
Since outdoor air is usually not in the hot comfort zone, the temperature that supplies the air is a concern of the design.
The supply system needs to solve this problem by adjusting or warming air in some way during periods when air is considered unacceptable.
For example, one way is to mix air with indoor air before it is supplied to the occupant. Standard 62. 2-
2004 there is no requirement for tempering.
As with the continuous exhaust system, there are two main designs: SinglePoint and multiplepoint systems. [
Figure 3 slightly]Single-
Point power supply system
In this strategy, the supply fan provides fresh air to the main room of the house through a small amount of pipes.
Through natural processes, air is distributed around the house.
Usually there is a return pipe in a separate room.
Low Cost of equipment;
Only fans and a small amount of pipes are required.
However, the supply air of the system is poorly distributed, especially for closed rooms in the House (
Luther and lstiblek 2000)
Even compared to singlepoint exhaust.
If you want to avoid comfortable complaints, the temperature adjustment or adjustment of this air is almost always needed. Multi-
Point power supply systemThe multi-
The advantage of the Point system is that the ventilation uniformity of the whole house is improved, but the additional installation cost of the plumbing works is high.
Because the flow rate of each power supply is low, the demand for tempering or adjustment may be reduced.
From the perspective of standard 62. 2-
2004, however, single-and multi-
Point power supply system.
The return side of the HVAC system has an inlet intermittent supply to integrate the supply air into the existing HVAC system, providing a low
The cost option to supply and distribute fresh air through the existing plumbing system is the most acceptable ventilation system for large production house builders (
Kevin Rudd and Lstiburek 2001).
In this system, the existing Central
Air systems are used to supply fresh air in a distributed manner through the pipes of buildings.
Place an external air inlet at the return of the HVAC system to allow fresh air to enter when the air handling fan is running (see Figure 4).
The intermittent operation of the central fan benefits all mechanical ventilation systems.
This leads to more uniform ventilation in each room of the House (
Luther and lstiblek 2000).
The ventilation system is operated intermittently, rather than continuously, Kevin Rudd (1999)
It is estimated that the total energy use can save 28% per year.
Research on computer modeling shows that cost
Compared with a separate supply ventilation system, the effectiveness of the system and the marginal cost of operation compared to no mechanical ventilation (
$3 to $27 a year)(
Luther and lstiblek 1998).
In addition, they estimate that it will take ten years to recover the initial cost of a separate pipe supply ventilation system.
According to computer modeling, the average outdoor air exchange rate of continuous and intermittent simulation systems is between 40 and 50 cfm, including the combined effects of ventilation and penetration.
These prices meet the standard 62-
1989, but not in compliance with the current standard 62. 2-2004. [
Figure 4 slightly]
The supply system can generate positive pressure in the house, so pressure relief vents are often installed.
We often see pressure relief through the rear ventilation damper of the bathroom and kitchen exhaust fan pipes, as well as the accidental leaking parts around windows, doors, or other building penetration.
Filtration can be added to the supplied air to remove contaminants.
The installation cost of the return entrance itself is the lowest;
Only a small amount of extra pipe is required, and a shock absorber may also be required.
Depending on the design, additional costs may be incurred by the control device and/or the damper.
The heat recovery potential for intermittent supply is low, because heat exchange occurs only when the exhaust gas is discharged through the fabric of the building. Currently air-
Processor fans meet the airflow rate standard in energy
Efficient way.
A simple control system can operate the system when the HVAC system is heated or cooled, or on a timer to supply fresh air when no heating or cooling is required (
Walker and Sherman 2003a, 2003b).
Maximize energy efficiency when the entire air distribution system is air-tight and located in air-conditioning space (
Luther and lstiblek 1998).
Exhaust and supply (Balanced)
The system balance ventilation system uses two fans with separate piping systems, one for supplying fresh air and the other for removing stale air from buildings (see Figure 5).
Unless the return path between supply and exhaust is blocked, the system should not affect the pressure balance of the internal space.
This ventilation strategy can be used effectively in any climate.
Heat exchangers can be included (or heat pump)
Recover heat from the exhaust gas and use it as a prerequisite for supplying air.
Extensive plumbing is used to provide fresh air to the living room and bedroom, while a separate exhaust system removes stale, usually damp air from the kitchen and bathroom.
Advantages include pre-filtration of supplying air and heat recovery of exhaust gas to save energy.
Some disadvantages include installation cost and maintenance cost (
Because there are multiple fans)
There may be fan noise (
For fans who do not meet the standard 62. 2-
2004 noise requirements).
Noise from fans (s)
The plumbing system can be transferred to each room of the House, reaching 30 to 40 dB.
Prairie and Passlack-Zwaans (1998)
Describes various strategies for sound insulation, including insulation pipes and preventing fan vibration.
Reducing the noise of the ventilation system has a positive effect on the indoor air quality, as it reduces the likelihood that the occupant will block the vent or close the system. [
Figure 5 Slightly]
The supply of continuous exhaust is integrated into the HVAC system.
If the house has an existing central force
The air system, which saves installation costs by integrating the supply inlet into the return of the HVAC system.
To remove the stale air, a separate exhaust fan runs continuously.
In a humid climate, this system can sometimes have problems, and the humid air is injected into the cooling air pipeline, resulting in condensation, which may require independent humidity control.
Supply with intermittent exhaust is integrated into the HVAC system.
In this strategy
Similar to above)
The exhaust fan will run intermittently.
In principle, the advanced control strategy can only be used to operate the exhaust fan when needed to replenish the return air.
No central house.
Air distribution system most new homes in the United States are built with central enforcement
But not all air systems.
Houses with radiation, hydro and/or baseboard systems may not have any central air distribution systems and may not be able to use any HVAC-
Integrated System discussed above.
However, any other system can be used to meet the standard 62. 2-2004.
However, if air distribution is a problem, some systems may perform better than others without central enforcementair systems.
If the building housing is tight, the exhaust system with drip holes or air intake can increase the possibility of getting outdoor air in each room.
A dedicated distribution system is required for a supply or balance method (i. e. , multi-point supply)
In order to achieve good air distribution.
All of the above systems are focused on mechanical ventilation solutions. Standard 62. 2-
2004 there is no mention of any other means of providing ventilation for new buildings, but it does allow (in Section 4. 1. 2)
If approved by an authorized design professional, other methods can be selected.
There are various potential ventilation options that do not require a fan.
Here we look at this sustainable technology with an understanding that does not meet standard 62. 2-
2004, but they do allow advanced solutions in the future.
Tradition: penetration with operable windows many existing homes rely on background ventilation through penetration of porous building shells, with operable windows to provide more ventilation when needed.
Natural climate forces create air pressure differences between the exterior and interior of the building, which can ventilate the building.
The pressure difference depends on the change of temperature and wind speed.
The wind has positive pressure on the windward surface of the building and negative pressure on the windward surface of the building (see Figure 6).
The resulting volume of ventilation depends on the position and number of openings in the building envelope, as well as the wind direction and speed.
This makes the ventilation rate unpredictable and uncontrollable as the drive mechanism is variable over the course of the year and the airflow path spreads over the building housing (
Allard and Ghiaus 2006).
The average ventilation rate is predictable, but the average ventilation rate is not a key factor in itself. [
Figure 6 slightly]
Sherman and Matterson (1997)
It has been shown that the annual average rate of change of air in typical existing houses exceeds one hour due to penetration;
Such high ventilation efficiency can meet the existing ventilation standards, so many existing houses do not require additional ventilation systems.
The cold, harsh climate, and the new residential buildings are three to four times closer, creating a tight building housing and the possibility of insufficient ventilation (
Sherman and Matterson 2002).
The basic system of this operable window does not have additional construction costs or clear operating costs.
The energy problem is almost entirely due to the need to regulate outdoor air.
The system relies on the occupant to open and close the windows to provide adequate ventilation, especially when the building envelope is tight;
However, when the envelope leaks, the control of the ventilation rate is poor.
Due to the high rate of change of air, lack of control can lead to energy loss, especially in winter with large temperature difference and wind speed.
Alternatively, the system may be poorly ventilated during the hot summer months.
When climate conditions are favorable, natural ventilation can be used to cool and replace air
Air conditioning system for part of this year.
But this open ventilation system has great limitations in the urban environment, including noise, safety and pollution (
Santamouris 2006).
The unique climate conditions of the city bring additional restrictions.
High temperature (
Island effect)
Lower wind speeds in urban canyons reduce the potential of natural ventilation systems. Geros et al. (2001)
Studying the air flow reduction of naturally ventilated buildings in the canyons of ten cities in Athens, Greece, it was found that due to the reduction of wind speed, the air flow through the building was reduced by 90%.
In buildings that use operable windows, there are some strategies to reduce noise, which can reduce traffic noise by 7. 5 to 8.
5 dB, does not affect the resistance of the airflow path (Oldham et al. 2004).
Since climate plays an important role in the effectiveness of natural ventilation, many groups have analyzed the suitability of various climatic conditions.
The potential of natural ventilation depends not only on the outdoor climate, but also on the design of the construction site and the construction site. Yang et al. (2005)
A model was created to assess the potential of a particular site to provide the natural force required to meet the ventilation criteria, with only natural ventilation.
It is clear that many of the climate conditions are too bad to use penetration as the primary source of ventilation.
On the contrary, in some climates, the driving force is too weak to serve as an actual source of major ventilation.
All of this leads to Wilson and Walker (1992)
Finally, \"there are no holes in all seasons.
\"Penetration does automatically provide ventilation without using any transport energy, but it almost always requires more space --
Provides the regulated energy of equivalent ventilation as a constant mechanical system.
Penetration can provide some heat recovery and filtration through the building housing, but unless well designed (e. g.
\"Dynamic insulation\" used in Scandinavia \")
It is unlikely to provide a lot of things.
Penetration depends on the weather, so there is no \"correct\" amount of air leakage.
To meet the average demand, penetration will always provide more ventilation than during extreme periods.
For more information on actionable windows and penetration, see the \"attached ventilation\" section below.
Passive chimney ventilation is designed to provide more control over natural ventilation rates by incorporating one or more chimneys or towers into the building structure to extract stale air as drip holes or blinds.
The passive chimney airflow is generated by a combination of two climatic forces: the difference between the temperature inside and outside and the wind speed.
Negative pressure at the top of the chimney is often a key factor.
As shown in Figure 7, in many cases, the wind speed creates negative pressure on the back wind side of the building.
A combination of cooler, incoming air and warmer, less dense indoor air, and negative pressure at the top of the chimney causes air to drain from the chimney.
Passive ventilation systems are rare in the United States, but are widely used in the European Union. Axley (2001)
Discover the most single in the UK and the Netherlands
Passive ventilation for family homes (
90% and 65%, respectively).
Emmerich and Dols (2003)
I used some of Axley\'s methods to create a passive ventilation design and analysis tool for multi-zone environments.
Stacking height and position is very important for keeping the negative pressure at the end of the stack and preventing reflow into the building.
The higher chimney is less sensitive to wind speed and direction.
Installation Guidelines and building codes reflect the importance of the chimney relative to the location of the roof.
Design and position various terminal covers to provide continuous negative pressure (
Independent of the wind direction)
At the stack exit (Axley 2001).
The chimney needs a larger diameter than the mechanical piping system to reduce the flow resistance under the condition of low pressure drop.
At present, there is not enough information to recommend a specific minimum or maximum value of performance parameters, but there are references worth considering, including those from AIVC database and Stephen et al. (1994).
A draft European standard for testing cowls and roof sockets is being prepared (prEN 131415). [
Figure 7 Slightly]
Ventilation flow in each room can change a lot.
Especially the rooms with upper and back winds may be poorly ventilated and it is easy to have no outdoor air.
Careful design measures can be taken to control and allocate traffic.
Typically, the system is designed with drip holes or blinds that can be manually adjusted to control the flow rate, but these effects are best when the uncontrolled penetration rate is low (
The building envelope is also very tight).
In order to freely distribute air, there must be a delivery grille or air vent in each room.
While these same standards are associated with mechanical ventilation, this problem is often more critical for passive ventilation due to low driving forces.
Many anecdotal cases suggest that the passive ventilation system has shown the ability to provide long enough
Short-term ventilation, but insufficient ventilation when short-term ventilation is required
Term for peak production of pollutants Qualcomm wind (i. e.
Bathing or cooking).
Because they are designed to be similar to mechanical systems but do not have mechanical components, passive stacked ventilation systems can reduce the cost of construction and operation of residential buildings.
During construction, the design of the interior space should be carefully considered to allow air to flow between the building rooms and to flow from the supply opening through the exhaust space.
A relatively larger pipeline is needed than the one used in the mechanical system, because flow resistance is a problem. Operating (air transport)
The cost does not exist;
However, there are usually some weather conditions in a year (
Low wind speed and/or small indoor/outdoor temperature difference)
Resulting in insufficient airflow.
There is essentially some uncertainty about the performance of any system that relies on natural driving forces.
There may be insufficient or excessive ventilation at certain times of the year (Yoshino et al. 2003).
Wilson and Walker1992)
Display even if there are several large passive ventilation openings, single
Insufficient ventilation in family homes (
Relative to standard 62-1989)
During the breeze (
Less than 10 kilometers per hour)
Or small temperature difference ([DELTA]10[degrees]C).
These are common in spring and fall.
At these times, proper ventilation can only be obtained if the occupant opens the window or otherwise supplements the system.
In cold days, the usual natural forces are the highest, resulting in excessive ventilation, air-conditioning and loss of energy. Self-
Adjusting the vent can reduce or control excessive ventilation. Pressure-
Sensitive breathing machines can provide constant ventilation at various pressures, but these passive control units are relatively scarce (Axley 2001). [
Figure 8:
Compared with mechanical systems in the field of filtration and thermal energy recovery, passive systems are insufficient.
The filtration of the supplied air is not feasible, and the heat recovery is also relatively rare. Shao et al. (1998)
The results show that the heat recovery efficiency of heat pipes is 50%.
Another strategy for heat recovery is to install the inlet vent to the bottom (see Figure 8).
This strategy will ease the supply of cold air, help to avoid the flow of cold air, and will also reduce the sensitivity of the ventilation rate to the wind direction (
Lin and Shan Tian 1996).
The solar chimney is a passive chimney system equipped with a solar collecting board (
Or glass walls often on the south side of the building)
Used to heat the air in the chimney, thereby increasing the buoyancy of the air in the chimney.
By increasing the temperature difference inside and outside the chimney, the ventilation rate was significantly improved on warm, sunny days with low wind speed (Bansal et al. 1994).
This can improve this year.
Circular validity of passive chimney ventilation system.
On a passive chimney without a solar chimney, the airflow rate can increase by 20% (
Jaros and Charvat 2004). Khedari et al. (2003)
The report said that the solar chimney can reduce the load in the air
Adjustment system (
Cooling by ventilation)
, Resulting in an average electrical savings of 10% to 20%.
The advantage of this system is that it increases the reliability of the passive stack system, and the system is silent and transparent for occupants.
The downside is the additional design, installation and cost of the solar glass panel.
This system is best suited to a sunny and warm climate.
Hybrid systems are passive systems with low levels
The Power fan promotes air flow through the chimney or vent, thus combining the advantages of the passive system with the reliability of the mechanical system.
The combination of the two systems improves indoor air quality while reducing energy demand through intelligent controllers (Fort Hays 2006;
Lee and Fort haisburg 2003).
These two systems can be combined in many ways.
The building may have two separate systems connected by a controller that can be switched from one system to another (
For example, mechanical exhaust fans in summer and winter and natural ventilation in moderate seasons).
Another combination is fan-
Auxiliary natural ventilation in which the main ventilation is provided by natural force but low
Power fans can be turned on to help ventilate during weak natural force.
Third, a similar strategy is to include a small fan in a passive stack system to help create the best pressure difference in the stack.
Yoshino et al. (2003)
It has been shown that even if weather conditions cause poor ventilation in the passive system, the mixing system can provide sufficient ventilation rate.
By using a fan at low wind speeds to improve chimney ventilation, insufficient ventilation is prevented.
By using damper control at the vent, excessive ventilation is prevented when the temperature difference is large.
Typically, these systems include the use of complex control systems such as carbon dioxide sensors, room temperature, airflow sensors, electric windows, and even weather stations (Dorer et al. 2004a).
Filtration of air supply is not common.
The main drawback of the hybrid system is the complexity of the control system.
This increases the additional cost of installing expensive parts and trained personnel.
Most residents feel comfortable (or prefer)
A simpler user interface.
With ventilation (Or uncertain)
Ventilation refers to features or effects that are not designed to provide an overall
The house is ventilated but in fact possible.
People don\'t \"calculate\" them in ventilation designs when they are really accidental, but, to determine the actual energy and indoor climate impacts of a particular design, one may need to consider these factors.
For example, air-to-
The air heat exchanger can only recover the energy of the air passing through it.
If the building leaks and a large part of the actual ventilated air goes around the exchange, the energy performance will be seriously affected.
In contrast, the performance of the exhaust heat pump, while not entirely independent, is less dependent on envelope airtightness.
Regardless of the ventilation system, the penetration and air leakage through the building envelope will adversely affect the ventilation effect.
Since the penetration rate depends on the weather, the penetration rate is not constant.
During the heating season, when the penetration rate is high, the house with mechanical and passive ventilation leaks will lose energy.
Heat recovery rarely occurs in building envelope (
Walker and Sherman 2003b)
, Which usually results in a loss of energy used to regulate the penetration of air.
When the air is bypassed by the heat recovery device, the balanced ventilation system also reduces performance.
However, too tight buildings can also reduce indoor air quality.
When the penetration is low, the mechanical exhaust system can generate negative pressure inside the house.
This may lead
Ventilation of combustion appliances, poor indoor air quality, high fan power requirements.
There are several ways to measure the leakage of building envelope (Sherman 1990;
Sherman and Chen 2006Ask 2003; Dorer et al. 2004b).
Ideally, the leakage of a building will not exceed the air required for healthy indoor air.
The amount of penetration will depend on the air tightness of the building, the difference in indoor and outdoor temperatures, and the wind force.
Tight building housing will provide minimal penetration ventilation and a ventilation system is required.
Penetration rates need to be considered when designing HVAC systems. Sherman (1995)
Created a penetration zone map that meets the requirements of standard 62-
1989 develop ventilation standards based on climate data in each region.
Mild climate (
Like the coast of California)
Penetration alone is not enough to provide adequate ventilation in newer wells
The penetration rate of insulated houses can be high in worse climate conditions, resulting in over-ventilation, energy loss and comfort problems.
The area needs the most rigorous building.
Most families require operating windows in each room.
When occupants control the ventilation system, they are more likely to feel comfortable and the windows provide a familiar ventilation system.
If used daily, windows can provide the ventilation required to meet the current specifications. Liddament (2001)
Reviewing several studies on occupant behavior and ventilation, it was found that windows are most likely to open under the following conditions: sunny days, higher occupant density, higher outdoor temperatures, low wind speeds, during cleaning or cooking activities and when smoking.
However, there are many cases where windows are not practical, such as noise, rain or strong winds, outdoor pollutants, cold ventilation, privacy, safety and safety issues, energy losses, etc. , or Windows may be difficult to operate.
These observations suggest that the opening or closing of the window is not always in order to meet the ventilation needs.
Local exhaust fans are often used in wet rooms to provide source control when needed, most often the kitchen and bathroom, but there may also be local exhaust fans for laundry and utility toilets.
The local exhaust fan is not intended to dilute the contaminants, but to remove them while the contaminants are still concentrated.
So they are a source control measure, not a ventilation in the normal sense.
While doing their sources
Demolition work, they may also increase the overall ventilation of the building, which in this sense is accidental ventilation.
For example, a high
Capacity of 400 cfm kitchen exhaust to ensure overall ventilation rate (temporarily)
At least 400 cfm, far above the minimum standard of 62. 2-2004 rates.
Because the working cycle of these local exhaust fans is determined by the occupants, presumably related to the source
Activities are generated and they cannot be expected to meet the minimum ventilation requirements.
One notable exception to the last statement is the \"double duty\" Bath fan.
In this design, the continuous running local exhaust fan meets the needs of local exhaust and overall exhaust at the same time.
The house was ventilated.
As long as the fan meets the appropriate requirements (e. g. , Size, noise), Standard 62. 2-
2004 this method is allowed. REAL-
World Factor standard 62. 2-2004--
Or any other ventilation standard or specification--
Is a set of minimum requirements, and if these requirements are followed, a certain minimum level will be provided for indoor air quality.
However, when deciding how to apply these requirements, there are a variety of real
World factors such as construction, installation and energy costs, control and distribution systems, and indoor air quality need to be taken into account.
Usually, these decisions are determined by the customer\'s needs (or builder)
More than the standard requirements (
Kevin Rudd and Lstiburek 2001).
There are potential problems when ventilation technology is not properly installed or designed (
Dorer and Breer 1998).
If the components are poorly manufactured or improperly installed, no ventilation system will achieve its performance potential.
In 2001, various performance tests were conducted on a recently built group of houses in Minnesota.
Sheltersource, Inc. (2002)
The survey found that the average measured exhaust volume of bathroom fans accounted for only 71% to 75% of the total exhaust volume.
Several factors, including the length of the long pipe, led to poor performance.
Compression in flexible pipes can also increase pressure drop by up to 9 times.
This leads to loss of ventilation rate and a significant increase in power and energy consumption in HVAC systems (Abushakra, etc. 2003).
Building air tightness is another area of building quality and building design as important as material in determining the ideal air tightness of building envelope (
Sherman and Chen 2006).
Ventilation requires not only energy to move the air, but also energy to regulate the supply of air.
In addition, costs are involved in the purchase, design and installation of equipment.
The use of ventilation and penetration of energy is important and can explain a-third to one-
Half of the space.
Regulating energy (
Sherman and Matterson 1993).
In developed countries, construction energy use accounts for about 40% of the total primary energy use.
Among them, the residential sector uses space adjustment of 60% to 70% (Orme 1998).
While providing a healthy ventilation rate, practical measures can be taken to save energy.
Including avoiding unnecessary changes in air (
Due to leaking buildings)
Use a good control strategy (
Do not open windows during heating and cooling)
Optimize fan and equipment efficiency. Orme (2001)
It has been shown that the loss of energy caused by air changes is as important as the loss of conduction and equipment.
If the building envelope is tight and the penetration is limited, the mechanical ventilation system can reduce the energy cost associated with air conditioning supply.
Sherman and Matterson (1993)
Estimate 2.
By tightening existing US housing stocks, 1 EJ can be saved each year.
Most homes in the United States use penetration as a ventilation system.
The average ventilation rate is estimated to exceed 1 ach, with an estimated energy load of 4 EJ per year.
If the existing housing stock is tightened and a continuous mechanical ventilation system is installed to provide a national average rate of air change of 0.
52 ach, the researchers estimated the energy load to be 1.
Cost savings of $2. 4 billion (
Sherman and Matterson 1997).
By installing a mechanical ventilation system with heat recovery, the energy consumption can be reduced by 9% to 21% (Hekmat et al. 1986).
In addition to energy costs, ventilation systems include additional costs for purchasing and installing equipment.
Table 1 compares the costs of various exhaust mechanical systems.
In Table 1, all ventilation systems operate continuously, but the cost estimate of running a central fan for mixed purposes (
This may be an option for some houses).
The results show that a single
The point exhaust system is the lowest cost of purchase and installation with an estimated total cost of $72.
This is supported by Wray et. al. (2000)
He also found that the operating cost of the mechanical exhaust system was the lowest. While a four-
Buying and decorating the energy recovery ventilation system will be the most expensive ($1772)
The benefits of improving air distribution, filters and energy conservation may exceed the initial cost.
As expected, it is more expensive to renovate the existing house than the newly built one, and more
Point allocation system ratio-point system.
If the house has an existing central fan system then it doesn\'t cost-
Supply ventilation system with single-point exhaust.
Although cost estimates are available, they are not necessarily sufficient to achieve the best option for ventilation systems.
Individual users may place high values on criteria that are not considered or have a large weight.
To evaluate so much
Different optimization methods are required for the target system.
For example, Robertson and others. (1998)
Developed unique optimization for overall cost-
Effectiveness of ventilation systems (
Including considerations for installation costs, operating costs, distribution efficiency, and potential for decompression and condensation). A multi-
It is found that the integral supply system is the best system as a whole.
The team recommended a balanced system in a Cold Climate (multi-
Single point power supply-point exhaust)
Prevent moisture problems in building walls.
In most cases, however, a simple continuous exhaust system will prove to be more costly
Effective if the only goal is to reach standard 62. 2-2004.
Climate can have a big impact on energy use.
In a hot and humid climate, it is necessary to remove moisture in houses with controlled ventilation systems.
According to Kevin Rudd and others. (2003)
Mechanical ventilation with an independent dehumidifying system provides the best overall value, including humidity control, installation costs, and operating costs.
Some of the key factors that lead to energy saving are positioning the pipe in the air conditioning space, using the insulation material, and installing high
Performance window.
Control various control systems from simple to complex, ventilation speed can be adjusted for comfort and energy saving.
Available systems include timers, occupant sensors, C [O. sub. 2]
Sensor and external temperature or humidity sensor.
The least reliable system is to rely on occupants to open and/or close windows.
The occupant will respond to the need for odor, airflow, noise or privacy, rather than a demand for a certain ventilation rate (Liddament 2001).
As the user wants to take advantage of the intermittent ventilation option with contaminants or weather, the area controlled by the ventilation of the residence will continue to grow
Sensitive mechanical systems, etc.
The distribution system provides uniform ventilation, which is an important part of all ventilation systems.
In general, the central exhaust system, as well as the natural and passive ventilation system, does not allocate fresh air or multiple
Point supply system or mechanical system using existing HVAC system pipelines (
Luther and lstiblek 2000).
These systems allow the supply of air to enter the building envelope in a rather uncontrolled manner, inevitably some rooms do not get enough air while others are over-ventilated.
The distribution system is an integral part of many mechanical ventilation systems that can have a significant impact on the ventilation rate and efficiency of buildings.
The leaking pipe is the source of energy loss, loss of ventilation rate, and in the case of returning pipes, it is the source of indoor pollution (Delmotte 2003).
Especially the location of the pipeline project is very important. Modera (1993)
When the pipe is installed in an unconditional space, the energy loss is 30% to 40%.
He also showed through on-site testing and modeling that the leakage through the mean piping system was 37% higher than the leakage that penetrated into the building envelope.
Houses with leaking pipes and air handling devices located outside the air-conditioning space have the risk of increasing penetration, especially in hot and humid climates.
This has a great impact on the actual ventilation rate of the average house.
Although the equipment is designed to provide adequate ventilation, the ventilation rate of many houses may not meet ASHRAE standards, as the leaking piping system can prevent the effective distribution of the supplied air.
One strategy to save air conditioning energy is to turn off registers or grilles in unused rooms.
This strategy can increase the pressure of the entire pipeline system and increase the leakage rate in the pipeline.
A recent study found that the energy saved by the air conditioner was only partially offset by an increase in the loss of the pipeline system (Walker 2003).
Indoor air quality exposed to indoor contaminants may pose a serious risk to health, especially in sensitive populations such as young, asthma, or older people (
Sherman and Hodgson 2004;
Seppanen and Fisk 2004).
Indoor pollution comes from indoors and outdoors and may exist in the form of suspended particles and volatile organic chemicals (VOCs), human bio-
Wastewater and microbial contaminants (Seppanen 2006).
Occupant activities such as cooking, bathing, smoking, vacuuming, use of cleaning products, painting, and chemical emissions of building materials, electrical equipment and appliances are examples of indoor sources.
Outdoor sources are mainly from automobile exhaust, but there are also agricultural activities, construction, manufacturing activities, ground sources (radon)
And allergens (Levin 2004).
The most effective way to control contaminants is to reduce or eliminate the source of emissions, but it is not always possible for some contaminants (
Sherman and Matterson 2003; Levin 2004).
There are many strategies to improve indoor air quality, including increasing ventilation rates to dilute contaminants, filtering to remove particulate matter or air cleaning to capture VOCs, or combining all three strategies.
Proper maintenance and operation of the ventilation system, limiting the appropriate architectural design of the pollution source, avoiding excessive decompression, and providing local ventilation where pollution is generated (
Combustion device)
Humidity control is an important strategy to control indoor air quality (
Hadlich and Grimsrud 1999).
Dilute ventilation.
The right whole
Indoor ventilation can dilute the level of indoor pollutants with fresh outdoor air (
Assume that the pollution in the outdoor air will not be more serious than the indoor air).
Dilution of contaminants with fresher air has always been a function of ventilation;
However, it is not a pollutant.
Not all contaminants can be treated in the same way.
Almost all ventilation techniques previously described can provide the ventilation rate required for effective dilution.
For natural ventilation and/or passive systems, there are some inherent deficiencies in the control of ventilation rate, which may lead to serious indoor pollution.
Although these systems can provide an average acceptable ventilation rate per year, they cannot effectively deal with peak periods of pollution (
Sherman and Wilson 1986.
On the other hand, all mechanical systems provide a high level of ventilation rate control so that indoor contaminants can be diluted at any time.
In addition, many mechanical systems also include local fans in areas with high pollutant production, such as bathrooms and kitchens, to minimize the spread of pollutants in other parts of the house.
In addition, the mechanical system can provide a higher ventilation rate required to dilute VOCs (such as formaldehyde) than needed to control human biological pollution
C. SewageO. sub. 2](
Sherman and Hodgson 2004;
Grimsrud and Hadlich 1999). Filtration.
Sherman and Matterson (2003)
It has been shown that Dilution ventilation is not always effective in reducing particle concentration.
Effective filtration can reduce the concentration of particles that cannot be reduced at the source;
This can also reduce the need for ventilation dilution.
There are several methods that can be used to reduce particle levels, including filtration, electrostatic dust collectors, and simply reducing particle levels by deposition that occurs in HVAC systems.
Margaret Thatcher and Leyton (1995)
It shows that the shell of the building provides almost no filtration of total particles, and the concentration of indoor particles is significantly affected by the level of activity of the residents of the house.
Even light activity such as walking can significantly increase the concentration of suspended particles of super micron particles. Wallace et al. (2004)
Display when the central fan is forced to be used,
The air system alone can reduce the whole
Concentration of housing particles (P[M. sub. 2. 5])
14%, and installed a
The pipe mechanical filter can reduce the particle level by 23%.
The electric dust collector can reduce particles by 51%, especially fine particles, but these are more expensive than mechanical filters and require daily maintenance to remain effective.
Filtration is most commonly used in mechanical ventilation buildings with supply systems and can be used to filter recycled air or filtered into supplied air.
The particle filter reports the value by ASHRAE minimum efficiency (MERV)scale (ASHRAE 1999).
The typical furnace filters are rated at MERV 4 or lower, and are not effective for removing inhaled particles, but they can remove large pollen and visible dust particles.
MERV filters of grades 6 to 8 can remove more small particles in the range of 10 [micro]m (P[M. sub. 10])
Filter with MERV rating of 9h [micro]
To 13 can remove small breathing 2. 5 [micro]m (P[M. sub. 2. 5])particles.
The current standard is 62. 2-
2004 it is recommended to use the MERV 6 filter to protect the HVAC system from particle build-up and make it itself a source of indoor contaminants.
Since residential HVAC systems are operating in cycles, the filter performance used as a part of HVAC systems is better when part is runningtime is high.
Fugler and Kuba (2002)
Display high-
The influence of high-efficiency furnace filter on indoor particulate matter is minimal (P[M. sub. 10])
When the occupant is active, but during the low activity time (sleeping), P[M. sub. 10]
Can reduce 70%
Selective filtering performance;
For the best particle size, it is generally less efficient and fails unless it is small in the installation and maintenance of the system (Liddament 2001).
If the building housing is tight and the filtration system is maintained, it is possible to reduce the level of indoor particles and the entry of outdoor particles into the indoor environment.
According to Sherman and Matterson (2003)
, The MERV 11 filter installed in the supply ventilation system can reduce cat and dust worm allergens by 30% to 40%.
They recommend the installation of MERV 9 to 12 filters, reducing pipe leakage, preventing filter bypass, reducing uncontrolled penetration, and running the fan continuously to maximize filtration efficiency.
High energy costs.
Outdoor pollution to nature (or passively)
Ventilated buildings, especially in urban areas.
Researchers have shown that outdoor particles are fully infiltrated (almost 100%)
Enter the indoor environment of the house with very leaking building envelopes and/or open windows, there is not much chance of interaction between these envelopes and envelopes (
Thatcher and Leiden 1995; Thatcher et al. 2001; Partti-Pellinen et al. 2000).
However, Canada\'s mortgage and housing companies (CMHC 2003)
It was found that the unfiltered exhaust system provides some outdoor particle protection compared to the unfiltered supply or balanced ventilation system.
These do not provide protection against the entry of outdoor particles.
Emmerich and Nabinger (2001)
The permeability coefficient was found to be 60% to 80% in the test room.
These studies show that the building housing provides some protection for pollen, allergens and diesel particles.
The ventilation system that supplies air by moving through the building housing (
Such as natural infiltration, passive system, mechanical exhaust system, etc)
Some minimal filtration can be provided from these types of outdoor particles.
CMHC found that the best protection for outdoor particles is provided by a ventilation system that pressurizes the house positively and uses a high
Efficiency Particle filter (HEPA)
It may be expensive.
In this case, the HEPA filter supply ventilation system is able to remove 99% of the outdoor particles. Radon.
However, in the case of radon, the mechanical exhaust system cannot always reduce the indoor radon concentration and may even increase the indoor radon concentration (Bonnefous and others. 1994).
This result is also applicable to other soil gas contaminants.
Researchers recommend a balanced ventilation system with heat recovery at Low radon concentrations, as well as an expensive floor ventilation system to reduce the inflow of radon into buildings. Sherman (1992b)
It has been shown that supply ventilation is generally better for radon control, but other ventilation types can work well depending on the climate and building type.
In this report, we review the literature and use our expertise to assess technologies that meet the ventilation requirements of residential buildings.
Our main goal is to meet the standard of 62. 2-
2004 requirement, but in doing so, we find that there are a lot of other issues that affect the actual decision about the installation of the house.
At present, there are various systems in the market that can be used to meet the standard 62. 2-2004.
While these systems typically fall into the category of supply, exhaust, or balanced ventilation systems, the specifics of each system are driven by concerns that go beyond the standard.
Some of these systems provide additional functionality (
Such as air distribution or pressure control).
The market will determine the direct value of these features, but ASHRAE may want to consider the relevant changes to the standard in the future.
ASHRAE may also want to consider expanding standards to allow sustainable technology ---
That is, passive or hybrid technology that relies primarily on natural driving forces rather than fans to transport air.
This system has been in use for thousands of years and is currently used in Europe to meet ventilation requirements.
Developing such systems for the US market is necessary because they have great potential in green buildings.
The report was co-produced by construction science and Lawrence Berkeley National Laboratory.
This project is through ARTI-
21CR job description: Project SI/IEQ-
30090. \"overall evaluation --
Mechanical ventilation system options--
The first stage of simulation research.
\"This work has also been supported by the assistant secretary for energy efficiency and renewable energy for the US Department of Energy Construction Technology ProjectDE-AC02-05CH11231.
Quote Abushakra, B. , I. Walker, and M. Sherman. 2003.
Study on pressure loss of residential air distribution system. Report LBNL-
Lawrence Berkeley National Laboratory, Berkeley, California 49700Allard, F. , and C. Ghiaus. 2006.
Natural ventilation in urban environments. In: M.
Santamouris and P. Wouters (eds. ).
Building Ventilation: state-of-the-art technology.
London: Earth scanASHRAE. 1999.
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