Ventilation calculator

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Requirements and standards

EN 15251 – European standard for indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics.

CR 1752 – Technical report: Ventilation for buildings – Design criteria for the indoor environment

Maximum CO₂ concentration – Calculation of airflow rate based on a selected maximum CO₂ concentration.

Maximum airflow rate – Estimation of CO₂ concentration based on a selected maximum airflow rate.

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Category

EN15251 - Perceived air quality:
Category 1 - High indoor air quality (15 % dissatisfied)
Category 2 - Good indoor air quality (20 % dissatisfied)
Category 3 - Moderate indoor air quality (30 % dissatisfied)

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The building´s release of pollutants?

When indoor building materials and furniture have an emission classification label, the indoor climate can be assumed to be low polluted.

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Activity levels

A typical average activity level is 1,2 met when designing ventilation for offices, schools, nursery, kindergartens etc.

Using an activity level of 1,2 met in this calculator follows the recommendations in Branchevejledning for indeklimaberegninger (Danish sector guideline for indoor climate calculations) for sedentary office work and schools, but also for nursery and kindergartens.
The previous mentioned sector guideline recommends using an activity level of 1,6 met for children in nursery and kindergartens, but with a reduction of the amount of CO₂ in the exhalation air for children corresponding to 45% of an adult person.
Only one activity level is required in this calculator to simplify the amount of input data. In this calculator the amount of CO₂ in the exhalation air for children in nursery and kindergartens are set to 60% of an adult person. Using an activity level of 1,2 met with a reduction of the CO₂ to 60% corresponds to the exact same amount of CO₂ as recommended in the national sector guideline for 1,6 met and a reduction of the CO₂ to 45%.
The following table lists various activity levels.

0.8 met - Lying down
1.0 met - Sitting, relaxed
1.2 met - Standing, relaxed
1.2 met - Sedentary work (office, school, laboratory)
1.6 met - Standing work (shop, laboratory, light industry)
2.0 met - Standing work
2.8 met - Medium physical exercise (heavy work in industry, workshop)
3.5 met - Walk (5 km/h)
7.5 met - Running (9 km/h)
9.5 met - Running (15 km/h)
15.0 met - Elite sports performer

Source reference:
Statens Byggeforskningsinstitut, Aalborg Universitet, Branchevejledning for indeklimaberegninger, 2017 (DK).
By og Byg anvisning 202, Naturlig ventilation i erhvervsbygninger: beregning og dimensionering (DK).
CR 1752, Ventilation for buildings – Design criteria for the indoor environment.

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How contaminated is the air outside the building?

Low – small city/country side: 380 ppm
Standard- middle-sized city: 400 ppm