Spain. The Spanish Technical Association of Air Conditioning and Refrigeration published an update on its recommendations to use air conditioning systems in an idea way, in addition to other important suggestions against Covid-19.
Since April 2020, the Atecyr Technical Committee has worked in an important way both in its Indoor Air Quality Working Group and in the REHVA Task Force. The Recommendations of Atecyr and its positioning were made in May and it can be said that it was a great contribution to the technicians of the air conditioning sector:
- It was warned that the airway is a route of transmission of the virus to be taken into consideration.
- The role of air conditioning installations as part of the solution to improve safety against contagion in buildings was highlighted.
- The need for the use of masks (not recommended by the administration at the time) was warned.
- It was recommended to prioritize the safety of users in the face of contagion over thermal well-being and energy efficiency.
- It was recommended to ventilate the spaces as much as possible as a means of safety against contagion. In this sense, a minimum flow corresponding to IDA-2 was recommended, pointing in any case to the change in the operation to maximize ventilation.
The Atecyr Recommendations were largely adopted by the Ministry for the Ecological Transition and the Demographic Challenge entitled "Recommendations for the Operation and Maintenance of Air Conditioning and Ventilation Systems of Buildings and Premises for the Prevention of the Spread of SARS-CoV-2" published in July, 2020.
Atecyr's Recommendations were made under the "ALARA" principle: "As Low As Reasonably Achievable" is "as low as reasonably achievable".
Zero risk does not exist, but after a few months of pandemic it can be said that the spaces that have been ventilated correctly, are very safe spaces from the point of view of the contagion of COVID-19. The precautions that are being taken in enclosed spaces such as good ventilation, use of the mask, cleaning and hygiene and distancing between people, make these places almost safe.
The safety of indoor spaces to avoid contagion is one of the keys to controlling the pandemic and maintaining work and social activity, until we have a solution to COVID-19 such as a vaccine or an effective treatment of the disease.
Objectives of the changes
It is proposed to make changes in the Recommendations of Atecyr, the result of increased knowledge of the behavior of the virus. The recommendations were published in May and that after 6 months, it is logical to make some changes to them. The changes are made taking into consideration, among other documents, the revision number 4 of REHVA in which the Atecyr Indoor Air Quality Working Group has worked.
Review of the Technical Committee on the positioning of Atecyr of May 7, 2020
The published Atecyr positioning document approved on May 7, 2020 remains mostly in force, as well as the Recommendations of the Atecyr Guide to Operation and Maintenance Recommendations. In this sense, it is valued that it has not been necessary to substantially modify the initial document published more than 6 months ago.
First, the pandemic has demonstrated the importance of ventilation in indoor air quality and the need to renovate facilities in this regard. From Atecyr we urge the administration to undertake a Plan to Help the Reforms of the Facilities for the Improvement of indoor Air Quality. The CAI working group that reviews the RITE makes proposals on how to contemplate in the revision of the RITE the incorporation of efficient ventilation systems in those buildings built before 2007. We consider that special importance should be given in the RITE those portable equipment intended for the well-being and hygiene of people (air purifiers, open home stoves,)
Any occupied space for non-residential use should be compulsorily equipped with forced ventilation. To this end, the administration should set a reasonable period to reform the existing facilities in this regard, since it is an aspect that affects people's health.
The importance of prioritizing safety and health before any other consideration, leads us to discourage the use of home equipment, built without any quality control and by unqualified personnel. Laptops must be CE marked, where the manufacturer indicates that they are compliant with certain requirements related to their quality and safety.
Forced ventilation is the only way to ensure proper ventilation of spaces. Whenever possible, ventilation should only be forced. If the "quality" of forced ventilation is sufficient, it is preferable not to open doors or windows, for the airflow between the impulsion diffusers and the return grilles to work properly.
If forced ventilation is not enough, natural ventilation should be used. Obviously, with more reason in spaces that do not have forced ventilation. In these cases, natural ventilation should be checked by CO2 probes, as it is the only way to verify adequate ventilation. Such a measure can be used for the control of the proper opening of doors and windows.
Continuous monitoring of the concentration of CO2 in the indoor environment is recommended in any case: natural, forced or mixed ventilation, since it allows you to verify in real time that the ventilation of the space is correct.
The minimum ventilation value in this pandemic situation must correspond to IDA2, that is, 12.5 L/s and person. The optimal ventilation value corresponds to IDA1, that is, 20 L/s and person.
Ventilation should be in operation two hours after use of the building and activated at least two hours before the entry of the first occupant. The occupancy schedule is marked in many cases by the cleaning or security service. The extraction of the toilets must be in operation 24 hours a day of the days where the building has occupation.
In the case of heat recuperators, if the leakage rate is maintained with a percentage of less than 3-5%, this is compensated by the contribution of outside air. The dilution of bioaerosols would be ensured with the contribution of outside air. Therefore, as long as this leakage rate is measured and guaranteed, the recuperator could be connected. In any case, fans that guarantee the ventilation of the spaces should never be stopped.
The use of purifiers should be considered as the last option, and is recommended when it is not possible to achieve the recommended ventilation levels. The HEPA filter is the first option, but it is not the only one. An ePM1 85% that guarantees a good air flow will always be better than a HEPA filter that reduces the air flow.
In addition, purifiers with ultraviolet light can be used as a complementary element, never with sole responsibility for indoor air quality, which must be guaranteed with ventilation and filtration. In this case, it is necessary to ensure: 1) confinement of the UVc unit; 2) guarantee of correct sizing and/or effectiveness; 3) guarantee of not emitting by-products such as ozone (very common with poor quality UVc units or with poorly sized systems).
In the case of small portable equipment, these must have a HEPA filter, the air diffusion is more limited and its condition is usually very localized, being convenient to analyze the possibility of installing more than one computer per local and close to the users. It is recommended that the flow rate be 3 to 5 movements / hour, corresponding to the volume of the premises calculated for a ceiling height of 2.7m.
The market offers a wide range of purifiers based on different disinfection techniques. This equipment can be used as a complementary element, when the options of ventilation and mechanical filtration (and / or electrostatic) have been exhausted, and never with sole responsibility for air quality.
Purification technologies must go through testing and evaluation protocols. Test to check their actual effectiveness and evaluation that they do not emit by-products of air treatment. Therefore, manufacturers must provide the tests and certifications that guarantee their efficiency and safety.
At this time, there are no certificates at the national level that guarantee the safety of these technologies. It is necessary to establish a methodology to certify that this equipment is efficient and safe.
Finally, it is considered that the capacity restrictions imposed by the administrations should be based on technical criteria. It is more appropriate to establish minimum separation distances (or m2 per occupant) + adequate ventilation, verified by CO2 measurement, rather than criteria of maximum % capacity, which are not based on any technical criteria of the specific space.
Aspects analyzed by the Atecyr Indoor Air Quality Working Group
Consideration 1. CE marked equipment
The use of home equipment, built without any quality control and by unqualified personnel, is discouraged.
Portable equipment must have CE marking, where the manufacturer indicates that the product complies with the essential safety requirements of the European Directives or the harmonized EN technical standards (European Standards) that affect the marketing of that product.
The manufacturer must draw up an EU Declaration of Conformity, demonstrating that the products and services made available to him are in conformity with certain requirements relating to their quality and safety.
Fixed equipment to be installed must have at least the following documents:
(a) Documents of origin, supply sheet and labelling;
b) copy of the manufacturer's warranty certificate, in accordance with Royal Legislative Decree 1/2007, of November 16, which approves the revised text of the General Law for the Defense of Consumers and Users and other complementary laws;
(c) documents of conformity or administrative authorisations required by regulation, including the documentation relating to the CE marking, where relevant, in accordance with the provisions transposing the European directives concerning the products supplied.
Consideration 2. Purifiers with HEPA filter
The use of purifiers should be considered as the last option, and is recommended when it is not possible to achieve the recommended ventilation levels.
Fixed purifiers can ensure a good diffusion of air in the space: air intake from the bottom and air impulsion in several diffusers or nozzles that ensure a good distribution of the purified air.
It is recommended that the flow rate be 3 to 5 movements / hour of the air volume of the premises, calculated as surface x ceiling height of 2.7 m. The HEPA filter is the first option, but it is not the only one. An ePM1 85% that guarantees a good air flow will always be better than a HEPA filter that reduces the air flow.
In the case of small portable equipment, they must have a HEPA filter, the air diffusion is more limited and its condition is usually very localized, being convenient to analyze the possibility of installing more than one computer per local. It is recommended that the flow rate be 3 to 5 movements / hour, corresponding to the volume of the premises for a ceiling height of 2.7 m.
The equipment must be provided with a control system that warns of the saturation of the filter. Filters must be replaced by qualified professionals, both in fixed and portable equipment.
Consideration 3. UVC ultraviolet purifiers
Purifiers with ultraviolet light can be used as a complementary element, never with sole responsibility for indoor air quality, which must be guaranteed with ventilation and filtration. In this case, it is necessary to ensure: 1) confinement of the UVc unit; 2) guarantee of correct sizing and/or effectiveness; 3) guarantee of not emitting by-products such as ozone (very common with poor quality UVc units or with poorly sized systems).
Consideration 4. Other purification technologies
The market offers a wide range of purifiers based on different disinfection techniques. This equipment can be used as a complementary element, when the options of ventilation and mechanical filtration (and / or electrostatic) have been exhausted, and never with sole responsibility for air quality.
Purification technologies must go through testing and evaluation protocols. Test to check their actual effectiveness and evaluation that they do not emit by-products of air treatment. Therefore, manufacturers must provide the tests and certifications that guarantee their efficiency and safety.
At this time, there are no certificates at the national level that guarantee the safety of these technologies. It is necessary to establish a methodology to certify that this equipment is efficient and safe.
Consideration 5. CO2 measurement
While this pandemic situation lasts, it is necessary to check the ventilation of the spaces. There are several methodologies to know the ventilation rate: measurement of the flow of the equipment, ballometers, CO2, tracer gases, etc. The CO2 measurement allows to determine the total ventilation of the space: forced and natural.
In case of forced ventilation, it may be enough to carry out some specific measure during a day with a portable equipment. Forced ventilation presents a lot of repeatability and does not depend on environmental conditions. Verification that the ventilation is correct.
Continuous monitoring is recommended in any case: natural, forced or mixed ventilation, since it allows you to verify in real time that the ventilation of the space is correct.
If there is a natural ventilation, the CO2 must be measured continuously, since it is the only way to verify the adequate ventilation. Such a measure can be used for the control of the proper opening of doors and windows.
CO2 sensors shall be certified by the manufacturer to have an accuracy of ± 75 ppm at concentrations of 600 and 1000 ppm at 25°C. It is recommended that sensors use NDIR (near infrared) technology so that the measurements have sufficient accuracy.
Consideration 6. Forced and natural ventilation
Ventilation must be forced, as this is the only way to guarantee proper ventilation of spaces. It is recommended to adapt the existing facilities to the requirements of the RITE currently in force. In fact, buildings whose facilities meet the requirements of the RITE are usually well ventilated.
Whenever possible, ventilation should only be forced. If the "quality" of forced ventilation is sufficient, it is preferable not to open doors or windows, for the airflow between the impulsion diffusers and the return grilles to work properly.
If forced ventilation is not enough, natural ventilation should be used. Obviously, with more reason in spaces that do not have forced ventilation. In these cases, natural ventilation should be checked by CO2 probes.
Consideration 7. After-hours ventilation
Ventilation should be in operation two hours after use of the building and activated at least two hours before the entry of the first occupant. The occupancy schedule is marked by the cleaning or security service.
Consideration 8. Toilet extraction
It is recommended to maintain the operating hours of the removal of the toilets, in 24 hours a day, on days when the buildings are occupied. In buildings that do not have occupancy on weekends and holidays, ventilation can be stopped during those days without occupation. It is recommended to start the extraction during the night before a day of occupation.
Consideration 9. Heat recuperators
It is considered that if the leakage rate is maintained with a percentage less than 3-5%, this is compensated by the contribution of outside air. The dilution of bioaerosols would be ensured with the contribution of outside air. Therefore, as long as this leakage rate is measured and guaranteed, the recuperator could be connected. In any case, fans that guarantee the ventilation of the spaces should never be stopped.
It is recommended to pay attention to the configuration of the geometry of the machines (see REHVA Recommendations document).
Consideration 10. Screens and ventilation
The use of screens can be effective in preventing transmission by drops.
However, aerosol transmission is not prevented with the use of screens. Moreover, in some situations it can block the air flow patterns in the premises and generate areas of air stagnation that increase the concentration of bioaerosols in specific areas generating situations of high risk.
It is recommended to limit the use of screens to a minimum and use them only in the positions with attention to the public where it is intended to avoid contagion directly (one person talking in front of the other).
Consideration 11. Drafts
Recirculated drafts should be avoided. They should not be a safety problem when drafts are produced by ventilation air (usually by natural ventilation). Indoor units must work at the minimum possible speed.
In the following link, you can download the new version of Atecyr's recommendations.
Source: Atecyr.
