1. WORKPLACE MEASUREMENTS IN A LOCAL BANK
Marianna Luoma

2. Background
The employees complained about draught in their offices (not the front desk)
The house manager asked us to do draught measurements
The measurements took place in February
The instrument used was Swema air CO Sensor
About the location of the measurement points
Measurement point 6 was close to the window

3. Swema air 300 -instrument Can be used to measure air movements
Omnidirectional probe
Measures continuously
Measurement duration may range from 15 seconds to 60 minutes
Gives draught rate (DR%)

4. DR=(0,37 v Tu+3,14)(34-Ti)(v-0,05) 0.62
DR = Draft rate, %
Ti = Air temperature, ºC
Tu = Turbulence intensity, %
V = Air velocity, m/s

5. *Supply air diffuser
*Positioned in the ceiling
*Horizontal air
diffusion direction

7. Swema air and CO2-meter at the table

10. Results Average values: Air temperature 21,7 ºC Air velocity 0,1 m/s
Draught rate 5 %
Note! Operative temperature was not measured. It was assumed
that operative temperature = air temperature

11. What is the optimal operative temperature for an office worker ?
Clothing 1 clo
Activity 1 met (sedentary person)
Air velocity 0,1 m/s
PMV = -0,07, when tº = 23 ºC
PMV = +0,20, when tº = 24 ºC

12. What is the optimal operative temperature for an office worker ?
Clothing 1 clo
Ativity 1,2 met (standing)
Air velocity 0,1 m/s
PMV = -0,33, when tº = 20 ºC
PMV = +0,10, when tº = 22 ºC

13. COMPARISON TO DRAUGHT CRITERIA: D2 and CR1752 D2: Design values for offices 21 ºC and 0.2 m/s

14. D2

15. Comparison to draught criteria: D2
The design value for indoor air temperature is 21 ºC according to the National Building Code of Finland, Part D2: Indoor Climate and Ventilation of Buildings
For the draught free conditions the maximum air velocity is 0,2 m/s
Based on this criteria, there was no draught

17. Comparison to draught criteria: CR1752
According to the EU report CR 1752 the highest draught rate in indoor class A is15%.
In the local bank, the highest measured draught rate was 11 %.
Based on this criteria, there was no draught.

18. How about the reality? Employees complained about draught
There are personal differences!
The mean values of the measurements do no help the person who suffers from draught!
Things like what we are doing, how we are dressed and how we like the thermal conditions, affect our feeling of draught.

19. Thermal conditions at the workplace
Operative temperature for normal office building is ºC
When the temperature is above this temperature or close to 24 ºC, our body tolerates higher air velocities compared to the situation when the temperature is closer to 21 ºC
Sensibility to draught increases when the temperature is below the optimal operative temperature
It is typical for Finland that indoor air temperature is close to 21 ºC which means that there is a high possibility for draught ….
Besides, some employees have their tables close to the cool window

20. What can we do?
In banks, there is a need for cooling even duringthe spring time → air flow rates and supply air temparatures have been designed based on the cooling needs → draught might occur
If we decrease the air flow rates and rise the supply air temperature, the warmer indoor air may be considered stuffy
The air flows could be readjusted and the diffusion directions of the supply air devices could be modified?
The type of diffuser could be changed?