Ac monitoring guidelines -
In addition, you have the ability to adjust and monitor the temperature settings in your home — directly from an app on the phone in your hand. If you have Google Home, Samsung SmartThings or Amazon Alexa connectivity, you can even use voice commands to adjust your HVAC system.
Essentially, you're turning your phone or smart device into a remote control that can manipulate various systems and functions in your home — HVAC among them. There are three different sensors that are placed throughout your HVAC system to monitor system activity.
How often do you think about your HVAC system throughout the year? Probably not too often unless it's causing you problems. It's important to keep up with routine maintenance on your HVAC units to prevent major problems from occurring and costing you a lot of money — but such issues may be avoided now by using a Smart AC.
A screen inside the app used to operate the system displays your system's stats. There, you should be able to monitor all the functions that are working and perhaps more importantly not working. Some examples of things detected by sensors that you can view on your app include:.
Everything costs something and nothing costs nothing where home ownership is concerned, but Smart AC is so bad considering the cash it can save you in plumbers, HVAC technicians and repair expenses. Other smart air conditioner monitors out there, such as Sensibo, have comparable prices.
Not only are you are able to be more energy-efficient thanks to the increased oversight, if you leave the home and forget to turn down the heat, you can do so from your phone now.
It helps to be aware of your energy usage levels and where that energy is most being used, so you can determine how and where to cut back. Since we're all home now more than ever, being prepared for unexpected home repairs with a plan from HomeServe is important.
See what plans are available in your neighborhood. Please check back soon. Blog Change Region HomeServe France HomeServe Spain HomeServe UK HomeServe USA. It looks like you're in Canada? We have Canadian website. Continue to Canada Save preference to Canada No, stay in the USA. HomeServe Logo Icon.
Because heat pumps are so energy-efficient, some state governments offer tax incentives or even direct cash rebates to homeowners who install air-source heat pumps, which sometimes make them the lowest-cost option for home heating and cooling.
Read our heat pump buying guide for more. Your contractor should ensure that duct sections are properly sized and that there are enough supply registers to deliver sufficient air to the right spots.
Undersized ductwork can lead to inefficient and noisy operation. Otherwise, air can escape, wasting 20 to 30 percent of the energy used to run your system. Sealing your ducts will keep you cooler in the summer and warmer in the winter.
For rough sizing guidance, check the Energy Star website. But the best option is to have your contractor do a load calculation based on a recognized method, such as one in Manual J from the ACCA. Efficiency This describes how much cooling the unit delivers for each watt of electricity.
Efficiency is expressed as the seasonal energy-efficiency rating, or SEER. The higher the SEER, the greater the efficiency. The minimum SEER allowed for a new split system central air conditioner in the U.
today is 14, which is at least 20 percent more efficient than minimum-efficiency models made even 10 years ago. Systems that meet the Energy Star guidelines for efficiency have a minimum SEER of The most efficient models reach a SEER of Manufacturers publish the noise levels for their products across a variety of outdoor temperatures and fan speeds, measured in decibels.
A lower rating is better, especially if the AC will be installed near a bedroom window. Consumer Reports members can see the predicted reliability ratings for 23 brands of central air conditioners , based on data that members have shared about the AC units they bought and installed in their own homes between and Central AC systems need regular maintenance for optimal performance.
Prices for such a service can vary widely. The contractor should also check to make sure that the system is properly charged with refrigerant, that there are no leaks, and that all mechanical components are working properly.
You can also handle some of the maintenance on your own. Clean grilles and filters monthly. Clear debris and dirt from condenser coils and check for blockages in the drainpipe.
In general, the thicker the disposable filter, the less often it needs to be changed. The HVAC filters we test last between three and 12 months.
If your HVAC system was installed before , it may rely on the refrigerant Freon, a trademark name for several different refrigerants including chlorofluorocarbons CFCs and hydrochlorofluorocarbons such as HCFC or R These chemicals deplete protective ozone from the atmosphere.
The Environmental Protection Agency phased out CFCs in the s and HCFCs in Better yet, consider replacing your AC system with a newer one. It will not only be better for the environment but more energy-efficient as well. Programmable thermostats. Setting your smart or programmable thermostat at the right temperature can reduce your cooling costs by about 10 percent.
The right temperature depends on your comfort level, but start by setting it at 78° F and experiment until you find the sweet spot. And keep in mind that using a box or ceiling fan, which costs little to run, can make you feel 3° F to 4° F cooler.
Outdoor space. The compressor needs adequate airflow to operate correctly , so make sure to keep at least 2 to 3 feet of space between the unit and any plants or structures. There should also be 5 feet of clearance between the top of the unit and any trees above. Ask around.
Seek referrals from neighbors, family, or business associates. Check their background. Check with your local Better Business Bureau and consumer affairs office for complaint records.
Get specifics.
Guideelines complete monitpring of helpful advice and survival Ac monitoring guidelines Astaxanthin and exercise performance every aspect of system monitoring and control. Have a specific question? Ask our team of expert monnitoring and Ac monitoring guidelines a specific answer! Whether you're new to our equipment or you've used it for years, DPS factory training is the best way to get more from your monitoring. Your HVAC system Heating, Ventilation, and Air Conditioner plays a critical role in keeping your remote locations online. It fights the damaging effects of an outside climate that may be too hot, too cold, too humid, or sometimes even not humid enough.Ac monitoring guidelines -
The higher the SEER, the greater the efficiency. The minimum SEER allowed for a new split system central air conditioner in the U. today is 14, which is at least 20 percent more efficient than minimum-efficiency models made even 10 years ago. Systems that meet the Energy Star guidelines for efficiency have a minimum SEER of The most efficient models reach a SEER of Manufacturers publish the noise levels for their products across a variety of outdoor temperatures and fan speeds, measured in decibels.
A lower rating is better, especially if the AC will be installed near a bedroom window. Consumer Reports members can see the predicted reliability ratings for 23 brands of central air conditioners , based on data that members have shared about the AC units they bought and installed in their own homes between and Central AC systems need regular maintenance for optimal performance.
Prices for such a service can vary widely. The contractor should also check to make sure that the system is properly charged with refrigerant, that there are no leaks, and that all mechanical components are working properly. You can also handle some of the maintenance on your own.
Clean grilles and filters monthly. Clear debris and dirt from condenser coils and check for blockages in the drainpipe.
In general, the thicker the disposable filter, the less often it needs to be changed. The HVAC filters we test last between three and 12 months. If your HVAC system was installed before , it may rely on the refrigerant Freon, a trademark name for several different refrigerants including chlorofluorocarbons CFCs and hydrochlorofluorocarbons such as HCFC or R These chemicals deplete protective ozone from the atmosphere.
The Environmental Protection Agency phased out CFCs in the s and HCFCs in Better yet, consider replacing your AC system with a newer one. It will not only be better for the environment but more energy-efficient as well. Programmable thermostats. Setting your smart or programmable thermostat at the right temperature can reduce your cooling costs by about 10 percent.
The right temperature depends on your comfort level, but start by setting it at 78° F and experiment until you find the sweet spot. And keep in mind that using a box or ceiling fan, which costs little to run, can make you feel 3° F to 4° F cooler.
Outdoor space. The compressor needs adequate airflow to operate correctly , so make sure to keep at least 2 to 3 feet of space between the unit and any plants or structures.
There should also be 5 feet of clearance between the top of the unit and any trees above. Ask around.
Seek referrals from neighbors, family, or business associates. Check their background. Check with your local Better Business Bureau and consumer affairs office for complaint records. Get specifics. An additional reference for assessing ductwork needs is Manual D.
The calculations produce a detailed, room-by-room analysis of cooling needs. Ask for a printout of all calculations and assumptions, including ductwork design. Be wary of a contractor who bases estimates merely on house size or vague rules.
We respect your privacy. All email addresses you provide will be used just for sending this story. Central Air Conditioning. Buying Guide Buying Guide Brand Reliability Brand Reliability. Sign In or Become a Member. Central Air Conditioning Buying Guide By Mary H. However, these codes do not address infection prevention in non-healthcare buildings and code minimum ventilation may be insufficient to protect indoor occupants under some circumstances e.
While large droplets micrometers [µm] and larger will settle to surrounding surfaces within seconds, smaller particles can stay suspended in the air for much longer. It can take several minutes for particles 10 µm in size to settle, while particles 5 µm and smaller may not settle for hours or even days.
Dilution ventilation and particle filtration are commonly used to remove these smaller particles from the air. Larger particles can also be removed using these strategies, but since they fall out of the air quickly, they might not have a chance to get captured by filtration systems.
The time required to remove airborne particles from a space can be estimated using Table B. The estimates assume the source of infectious particles is no longer present in the space. Although there are some highly contagious airborne diseases like measles where CDC provides specific guidance for However, perfect mixing usually does not occur.
Removal times will be longer in rooms or areas with imperfect mixing or air stagnation. This factor represents how well the ventilation system mixes and dilutes the concentration of airborne particles within the room. In that case, the time identified from Table B.
Nonventilated or poorly ventilated spaces have typical values of k ranging from 8 to Increased ACH generally leads to reductions in k, although k can also be reduced by the use of a fan in the space, which does not have an impact on ACH. Ultimately, wait times can be reduced by increasing ACH, reducing k, or a combination of both.
Example 1. Solution: Since Q e is larger than Q s by 15 cfm, the heating, ventilation, and air conditioning HVAC system is pulling 15 cfm of air into the room from adjacent areas i. For this example, the 15 cfm of transfer air is assumed to be free of infectious airborne particles.
Calculate the air changes per hour:. Using Table B. Note: Determining the true value of the mixing factor is difficult and requires special equipment to measure air flows and conduct tracer gas decay testing.
Thus, conservative estimates of k are often used as described above. Also, the addition of an air cleaning device e. The flow rate from the air cleaning device can be added to Q determined above, which will increase the overall ACH in the room.
The air movement created by the air cleaning device can also decrease the value of k. Together, the increased ACH and decreased k can help substantially reduce wait times. See Example 2 at the bottom of FAQ 5 for more information, including an example of the calculations.
Yes, filters with higher collection efficiencies can provide significant reductions in viral particle concentrations. This standard was developed by ASHRAE, a global society focused on building systems, indoor air quality, and sustainability in the built environment.
Based on the filtration efficiency determined by the testing procedures, filters are assigned a Minimum Efficiency Reporting Value MERV.
MERV values range from 1 to 16 and higher MERV values correspond to more efficient filters. Research shows that the particle size of SARS-CoV-2 is around 0.
However, the virus generally does not travel through the air by itself. These viral particles are human generated, so the virus is trapped in respiratory droplets and droplet nuclei dried respiratory droplets that are larger than an individual virus. Most of the respiratory droplets and particles exhaled during talking, singing, breathing, and coughing are less than 5 µm in size.
CDC recommends using MERV 13 filters or filters with the highest efficiency possible, without having detrimental effects on overall HVAC system performance.
Alternatively, other effective air cleaning technologies can also be used to help meet this performance target. Collectively these particles are capable of remaining airborne for hours and are most associated with deep lung penetration.
Efficiencies for MERV 15 and MERV 16 filters are even higher. Increasing filtration efficiency can increase the pressure drop resistance to air flow across the filters.
Scientific developments in filter design and manufacturing have reduced the amount of the increased pressure drop and its resulting impact on HVAC operations, but not all filters have adopted the newer technology.
Prior to a filtration upgrade, the specific filters under consideration should be investigated for their pressure drop ratings at the flow rate s of intended use and the potential impacts of that pressure drop evaluated against the capabilities of the existing HVAC system.
High-efficiency particulate air HEPA filters are even more efficient at filtering human-generated infectious particles than MERV 16 filters. However, outside of a few unique applications, HEPA filters are rarely used in central HVAC systems.
Directional airflow is a protective ventilation concept where air movement flows in a clean-to-less-clean direction. The creation of directional airflow can be accomplished within a particular space or between two adjacent spaces.
This can be done passively, through intentional placement of supply and exhaust heating, ventilation, and air conditioning HVAC grilles, or by the intentional creation of pressure differentials between adjacent spaces through specification of offset exhaust and supply air flow rates.
Creation of the directional airflow can also be done actively, through the use of fans exhausting through open windows, strategic placement of ductwork attached to in-room HEPA filtration units, or dedicated exhaust systems installed or portable that generate a desired airflow by exhausting air out of windows, doorways, or through temporary ducts.
In specific settings, specialized local control ventilation interventions that establish the desired airflow directions can also be used see the NIOSH Ventilated Headboard. Directional airflows must be evaluated carefully. By definition, a High Efficiency Particulate Air HEPA filter is at least This 0.
Thus, HEPA filters are no less than These viral particles are human-generated, so the virus is trapped in respiratory droplets and droplet nuclei dried respiratory droplets that are larger.
The excellent capture efficiency of HEPA filters comes at a cost, namely the significant pressure drop and energy required to move air through the HEPA filter. For this reason, most traditional HVAC systems are not able to use HEPA filters and are limited to the use of less-efficient filters.
To account for the increased pressure requirements, HEPA filtration units often combine a HEPA filter with a dedicated fan system. In-room HEPA air cleaners that combine a HEPA filter with a powered fan system are a preferred option for auxiliary air cleaning, especially in higher risk settings such as health clinics, vaccination, and medical testing locations, workout rooms, or public waiting areas.
Other settings that could benefit from in-room HEPA filtration can be identified using typical risk assessment parameters, such as community incidence rates, facemask compliance expectations, and room occupant density.
While these systems do not bring in outdoor dilution air, they are effective at cleaning air within spaces to reduce the concentration of airborne particulates, including SARS-CoV-2 viral particles.
Thus, they give equivalent air exchanges without the need for conditioning outdoor air. In choosing an in-room HEPA air cleaner, select a system that is appropriately sized for the area in which it will be installed. This determination is made based on the air flow through the unit, which is typically reported in cubic feet per minute cfm.
The CADR is an established standard defined by the Association of Home Appliance Manufacturers AHAM. The CADR is generally reported in cfm for products sold in the United States.
The paragraphs below describe how to select an appropriate air cleaner based on the size of the room in which it will be used. The procedure below should be followed whenever possible. If an air cleaner with the appropriate CADR number or higher is not available, select a unit with a lower CADR rating.
The unit will still provide incrementally more air cleaning than having no air cleaner at all. In a given room, the larger the CADR, the faster it will clean the room air. Three CADR numbers are given on the AHAM label, one each for smoke, dust, and pollen.
The smoke particles are the smallest, so that CADR number applies best to viral particles related to COVID and other viral respiratory diseases. The label also shows the largest room size in square feet [ft 2 ] that the unit is appropriate for, assuming a standard ceiling height of up to 8 feet.
If the ceiling height is taller, multiply the room size ft 2 by the ratio of the actual ceiling height ft divided by 8. The CADR program is designed to rate the performance of smaller room air cleaners typical for use in homes and offices.
For larger air cleaners, and for smaller air cleaners whose manufacturers choose not to participate in the AHAM CADR program, select a HEPA unit based on the suggested room size ft 2 or the reported air flow rate cfm provided by the manufacturer.
Consumers might take into consideration that these values often reflect ideal conditions which overestimate actual performance. For air cleaners that provide a suggested room size, the adjustment for rooms taller than 8 feet is the same as presented above. If the ceiling height is taller, do the same calculation and then multiply the result by the ratio of the actual ceiling height ft divided by 8.
Using ductwork and placing the HEPA system strategically in the space can help provide desired clean-to-less-clean airflow patterns where needed. Example 2.
Solution: The addition of the HEPA filter device provides additional clean air to the room. Thus, the increased ACH and lower k value associated with the portable HEPA filtration unit reduced the wait time from the original 5 hours and 45 minutes to only 1 hour and 24 minutes, saving a total of 4 hours and 21 minutes before the room could be safely reoccupied.
Adding the portable HEPA unit increased the equivalent ventilation rate and improved room air mixing. Yes, when an appropriate dose of UVGI is applied. Ultraviolet germicidal irradiation UVGI , otherwise known as germicidal ultraviolet GUV , is an air and surface treatment tool used in many different settings, such as residential, commercial, educational, and healthcare settings.
The technology uses ultraviolet UV energy to inactivate kill microorganisms, including viruses, when designed and installed correctly. UVGI can inactivate viruses in the air and on surfaces. Seek consultation with a reputable UVGI manufacturer or an experienced UVGI system designer prior to installing UVGI systems.
These professionals can assist by properly designing, installing, and commissioning the system for your specific setting. In addition, the site where the product is manufactured may also require registration.
Upper-room UVGI Upper-room or upper-air UVGI uses specially designed UVGI fixtures mounted on walls or ceilings to create a treatment zone of ultraviolet UV energy that is focused up and away from people. These fixtures treat air as it circulates from mechanical ventilation, ceiling fans, or natural air movement.
The advantage of upper-room UVGI is that it treats the air closer to and above people who are in the room. Since the s, UVGI systems have been widely used for control of tuberculosis TB.
The CDC guidance Environmental Control for Tuberculosis: Basic Upper-Room Ultraviolet Germicidal Irradiation Guidelines for Healthcare Settings provides information on appropriate UVGI system design, related safe operation, and maintenance.
Based on data from other human coronaviruses, a UVGI system designed to protect against the spread of TB should be effective at inactivating SARS-CoV-2 and therefore prevent spread.
While small spaces may require a single UVGI fixture, most UVGI systems usually require multiple UV fixtures to be effective. For example, a rectangular-shaped waiting room with 10—30 occupants will require 2—3 upper-air UVGI fixtures.
As part of system installation, care must be taken to control the amount of UV energy directed or reflected into the lower occupied space. Reputable UVGI manufacturers or experienced UVGI system designers will take the necessary measurements and make any required adjustments to prevent harmful UV exposures to people in the space.
Potential Application: Can be used as an additional layer of protection to treat the air kill germs in indoor spaces; most useful in spaces that host large gatherings or where the risk of disease transmission is high.
In-duct UVGI In-duct UVGI systems are installed within a heating, ventilation, and air conditioning HVAC system. These systems are designed to serve one of two purposes:. These devices produce relatively low levels of UV energy. This energy is continually delivered 24 hours a day, which is why they are effective.
Coil treatment UVGI devices are not designed for treating the air and should not be installed for this purpose. Potential Application: Can be used to reduce HVAC maintenance and improve operational efficiency within large, commercial HVAC systems or residential HVAC systems; not recommended for inactivating airborne pathogens.
HVAC air treatment UVGI systems generally require more powerful UV lamps or a greater number of lamps, or both, to provide the necessary UVGI required to inactivate pathogens in a short period of time. Air treatment systems are often placed immediately downstream of the HVAC coils. This location keeps the coil, drain pan, and wetted surfaces free of microbial growth and also treats the moving air.
Potential Application: Can be used inside any HVAC system to reduce the concentration of infectious airborne pathogens. Whole-room UVGI Whole-room UVGI commonly referred to as Far-UV uses specially designed UVGI fixtures mounted on walls or ceilings to create a treatment zone of ultraviolet UV energy that extends throughout an occupied space.
While standard UVGI fixtures emit UV energy at a wavelength around nanometers nm , far-UV devices use different lamps to emit UV energy at a wavelength around nm. Aside from the wavelength, a major difference between the two technologies is that standard UVGI systems are generally designed to avoid exposing people to the UV energy, while many far-UV devices are marketed as safe for exposing people and their direct environment to UV energy.
Recent research has indicated nm energy is much safer for humans than once thought. In fact, the American Conference of Governmental Industrial Hygienists ACGIH recently increased their Threshold Limit Values TLVs 7-fold for eyes and over fold for skin exposed to nm energy.
This increase was in response to data showing nm energy does not penetrate the tear layer of the eye or the layer of dead skin stratum corneum that protect living skin beneath. Research studies also indicate that far-UV wavelengths can effectively inactivate microorganisms, including human coronaviruses, when appropriate UV doses are applied under experimental conditions.
However, there are still some questions about how effective nm energy can be in real occupied spaces against human-generated pathogens when UV exposures are controlled to safe limits. Far-UV is a promising technology that may well prove to be effective at treating air and surfaces, without some of the safety precautions required for standard UVGI.
Due to the potential promise this technology represents, there are substantial private and public research activities underway to further validate claims of safety and efficacy.
In the near term, whole-room UVGI is best viewed as new and emerging technology. Consumers considering an emerging technology such as Far-UV should read FAQ 8 on emerging technologies below. Potential Application : Air and surface treatment in occupied indoor environments.
CDC recommends using technologies that are known to work and will not cause harm. Be cautious when considering an emerging new technology. Do your homework, to include requesting proof of performance and safety under real-world, as-used conditions.
CDC does not provide recommendations for, or against, any manufacturer or product. There are numerous technologies being heavily marketed to provide air treatment during the ongoing COVID pandemic. Common among these are ionization, dry hydrogen peroxide, and chemical fogging.
Some products on the market include combinations of these technologies. These products generate ions, reactive oxidative species ROS, which are marketed using many names , or chemicals into the air as part of the air treatment process.
People in spaces treated by these products are also exposed to these ions, ROS, or chemicals. Some research has found these exposures may be harmful under certain conditions, including high concentrations or vulnerable populations.
While variations of these technologies have been around for decades, relative to other air cleaning or treatment methods, they have a less-documented track record when it comes to treating large and fast volumes of moving air within heating, ventilation, and air conditioning HVAC systems or even inside individual rooms.
This does not necessarily imply the technologies do not work as advertised. As with all emerging technologies, consumers are encouraged to exercise caution and to do their homework. Consumers should research the technology, attempting to match any specific claims against the intended use of the product.
Consumers should request testing data that quantitively demonstrates a clear protective benefit and occupant safety under conditions consistent with the intended use. When considering air treatment technologies that potentially or intentionally expose building occupants, the safety data should be applicable to all occupants, including those with health conditions that could be aggravated by the air treatment.
In transient spaces, where average exposures to the public may be temporary, it is important to also consider occupational exposures for workers that must spend prolonged periods in the space. Preferably, the documented performance data under as-used conditions should be available from multiple sources, some of which should be independent, third-party sources.
Unsubstantiated claims of performance or limited case studies with only one device in one room and no reference controls should be questioned. At a minimum, when considering the acquisition and use of products with technology that may generate ozone a gas with potentially harmful health effects , verify that the equipment meets UL standard certification Environmental Claim Validation Procedure ECVP for Zero Ozone Emissions from Air Cleaners which is intended to validate that no ozone is produced.
Yes, carbon dioxide CO 2 monitoring can provide information on ventilation in a given space, which can be used to enhance protection against COVID transmission.
Strategies incorporating CO 2 monitors range in cost and complexity. However, greater cost and complexity does not always mean greater protection. Limited information exists regarding a direct link associating CO 2 concentration to a risk of COVID transmission.
Changes in CO 2 concentrations can indicate a change in room occupancy and be used to adjust the amount of outdoor air delivered. However, CO 2 concentrations cannot predict who has COVID infection and might be spreading the virus, the amount of airborne viral particles produced by infected people, or whether the HVAC system is effective at diluting and removing viral concentrations near their point of generation.
Ventilation based on CO 2 measurements cannot recognize the increased risk of transmission when multiple room occupants are infected. In some well-designed, well-characterized, well-maintained HVAC environments, the use of fixed CO 2 monitors can be informative. When used, these monitors are often incorporated into demand-controlled ventilation DCV systems that are designed with a primary intent of maximizing energy efficiency through reductions in outdoor air delivery.
However, during times of high community transmission, guidance is often to deactivate DCV systems and exceed minimum ventilation whenever possible, in addition to enhanced filtration, and other intervention-focused considerations. Traditionally, CO 2 monitoring systems are expensive, require extensive knowledge to accurately install and set up, and require sophisticated control programs to effectively interact with the building heating, ventilation and air conditioning HVAC systems in real time.
They were not designed to protect building occupants from disease transmission. Fixed-position CO 2 monitors measure CO 2 concentration as an indicator of the number of people in the space.
As the CO 2 concentration increases, the HVAC DCV system increases the amount of outdoor air ventilation in the space to dilute CO 2 and vice versa. The number of CO 2 sensors, the placement of those sensors, and their calibration and maintenance are collectively a large and complex issue that must not be overlooked.
For example, the CO 2 concentration measured by a fixed, wall-mounted monitor may not always represent the actual concentrations in the occupied space.
If air currents from the room HVAC, or even make-up air from windows, flows directly over this monitor location, the corresponding concentration measurements will be artificially low. If the room has good air mixing, the measured concentration should approximate the true concentration, but rooms are rarely well mixed, particularly in older buildings with aging ventilation systems or none at all.
This may result in elevated CO 2 concentrations in those other spaces which the HVAC system is unable to control. A more modest, cost-efficient, and accurate use of CO 2 monitoring is the use of portable instruments combined with HVAC systems that do not have modulating setpoints based on CO 2 concentrations.
It is critical to select calibrated CO 2 meters whose sensors are reliable and accurate to draw meaningful inferences from measured indoor CO 2 concentrations. Under this approach, validate that the HVAC system is operating appropriately and is meeting or exceeding code-minimum outdoor air requirements based on current use and occupancy.
Next, measure the resulting CO 2 concentrations in rooms under as-used conditions using a handheld portable CO 2 meter.
These observations will be the CO 2 baseline concentrations for each room under the HVAC operating conditions and occupancy levels. One potential target for the baseline concentrations that is used to represent good ventilation is CO 2 readings below parts per million ppm. It is important to note, however, that a single concentration value may not be an appropriate target for all space types and occupancies for the purposes of assessing the ventilation rate see ASHRAE Position Document on Indoor Carbon Dioxide.
Once a target concentration is identified, compare your baseline concentrations to the target concentration. If a baseline measurement is above the target, reevaluate the context under which the measurement was obtained and if warranted, investigate the ability to increase outdoor air delivery.
If unable to get below your target CO 2 value, increased reliance on enhanced air filtration including in-room HEPA air cleaners may be necessary. Once the baseline concentrations are established, take periodic measurements in each space and compare those to the initial baselines. Generally, no.
Temperature and humidity can both influence the transmission of infectious diseases, including COVID, but that influence has practical limitations in occupied spaces of buildings. Research on the impact of temperature has shown that SARS-CoV-2, the virus that causes COVID, is sensitive to elevated temperatures, with over However, this temperature is far outside the limits of human comfort and could damage some building materials.
While temperatures lower than 70°C °F are also effective, the required exposure time for inactivation increases as the temperature decreases.
So, elevated temperatures offer the potential for decontamination of SARS-CoV-2 virus in the air or on surfaces, but the use of increased temperature solely for decontamination is not generally recommended and is not realistic for occupied spaces.
Based on current evidence, it is not clear whether, in practice, increasing humidity could significantly reduce transmission of COVID beyond the reductions that result from using good ventilation and filtration.
Several scientific research studies have concluded that influenza and SARS-CoV-2 viruses do not survive as well in environments with higher humidity compared with lower humidity. However, the reasons for this are unclear, and artificial experimental factors like the size of the liquid droplets used in the experiments and the composition of the liquid containing the viruses affect the results.
Thus, there is still debate within the scientific community over how much humidity affects virus survival outside of the laboratory. Adding humidity to indoor environments, especially in very cold climates, can also introduce additional challenges to the building environment.
CDC and standards-setting organizations like ASHRAE do not make recommendations about controlling indoor humidity to reduce virus survival, although humidity recommendations are made for other reasons, such as prevention of dust mite and mold growth or reduction of static electricity.
While fans alone cannot make up for a lack of outdoor air, fans can be used to increase the effectiveness of open windows, as described in the CDC list of ventilation mitigation strategies.
Fans can also be used indoors to improve room air mixing. Improved room air mixing helps distribute supplied clean air and dilute viral particle concentrations throughout the room, which reduces the likelihood of stagnant air pockets where viral concentrations can accumulate.
As with all fan use during the COVID pandemic, take care to minimize the potential to create air patterns that flow directly across one person onto another:. Fans can also enable clean-to-less-clean directional airflow. Such applications should be evaluated closely to avoid unintended consequences and only adopted when supported by a safety risk assessment.
Barriers can physically separate spaces that are next to each other. When used for infection control, the barrier is intended to prevent someone on one side of the barrier from exposing a person on the other side of the barrier to infectious fluids, droplets, and particles.
Whether a barrier interferes with improved ventilation depends on how it is installed. Protective barriers can sometimes help improve ventilation, but they can sometimes hinder ventilation too.
Sometimes they have no effect on ventilation. Protective barriers can assist with improved ventilation when used to facilitate directional airflows or desired pressure differentials between clean and less-clean spaces.
The barrier can be aligned with the intended airflow to help direct it towards a desired location, such as an HVAC return air grille or an in-room HEPA air cleaner inlet.
With a person guidelined Ac monitoring guidelines generating guidelibes, this table would Ac monitoring guidelines apply. Other equations are monltoring that include a constant generating source. However, certain diseases e. The times given assume perfect mixing of the air within the space i. However, perfect mixing usually does not occur. Removal times will be longer in rooms or areas with imperfect mixing or air stagnation.
Ventilation is a term with Ac monitoring guidelines meanings to different guidelinnes. When Ac monitoring guidelines, guidlines mitigation strategies cA help reduce viral particle concentration. The lower the concentration, Gudielines less likely viral particles can be inhaled into the lungs potentially lowering the inhaled dose ; contact eyes, nose, and mouth; or fall out of the air to accumulate on surfaces. Not all interventions will work in all scenarios and their selection must be carefully evaluated prior to adoption. These ventilation interventions can reduce the spread of disease, but they will not eliminate risk completely. 
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