FM Nectar

Presented by Ian Mawditt

Can we rely on good ventilation?

IAQ and ventilation effectiveness

February 2017

London

Healthy Buildings Conference slide 2

Slide from Tom Woolley presentation, October 2016

Healthy Buildings Conference slide 3

Slide from Tom Woolley presentation, October 2016

Healthy Buildings Conference slide 4

Contents

Ventilation performance summary – how are we doing?

Ventilation effectiveness overview – results from field

monitoring:

House Dust Mites

Carbon Dioxide

TVOCs

Nitrogen Dioxide

Radon

Summary – can we rely on good ventilation?

Healthy Buildings Conference slide 5

0

1

2

3

4

5

6

7

8

9

10

40-60% 60-80% 80-100% 100-120% 120-140% 140-160% 160-180%

Nu

mb

er o

f H

om

es

% of Required EQA

Installed ventilator area vs. AD F minimum specification

Data from DCLG 2009: Ventilation and IAQ in Part F 2006 homes study

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Ventilation extract rates in new homes: continuous MEV

Site 1 Site 3 Site 4 Site 5 Site 6

Design 43.00 37.00 45.00 31.00 15.00

ZCH Measured 20.80 19.10 21.00 12.30 5.50

% of Required Duty 48 52 47 40 37

0.00

10.00

20.00

30.00

40.00

50.00

litre

s p

er s

eco

nd

Chart for Zero Carbon Hub: Ventilation in New Homes study

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Measured flow rates – MVHR

Minimum boost rate met in:

44% kitchens

71% bathrooms

30% en-suites

38% utility rooms

Minimum supply air flow rates

met in 33% of dwellings

0.00

5.00

10.00

15.00

20.00

25.00

Kitchen Bathroom En Suite Utility W.C.

Litr

es p

er s

eco

nd

(l.s

-1)

Minimum AD F

Chart from Characteristics and performance of MVHR systems (meta study): MEARU/OISD/Fourwalls

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Successful ventilation installation

requires a full house of happy

faces!

One unhappy face in the chain

(row) will likely result in failure.

None of the sites visited in this

study had a complete row of

happy faces.

None of the ventilation systems

met the minimum requirements

specified in AD F

Chart by Zero Carbon Hub: Ventilation in New Homes study

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30.00

35.00

40.00

45.00

50.00

55.00

60.00

65.00

70.00

75.00

80.00

16.00 17.00 18.00 19.00 20.00 21.00 22.00 23.00 24.00

Rel

ativ

e H

um

idit

y (%

)

Temperature (oC)

No PP Ventilation PEH 7g.kg CEH min (DP2)

Hygrothermal conditions without purpose-provided ventilation

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Hygrothermal conditions with purpose-provided ventilation

30.00

35.00

40.00

45.00

50.00

55.00

60.00

65.00

70.00

75.00

80.00

16.00 17.00 18.00 19.00 20.00 21.00 22.00 23.00 24.00

Rel

ativ

e H

um

idit

y (%

)

Temperature (oC)

No PP Ventilation With PP Ventilation PEH 7g.kg CEH min (DP2)

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Seasonal performance – MVHR and non-MVHR

CO2 data from 43

monitored homes

CO2 levels higher in non-

MVHR dwellings through

spring and summer

Increasing CO2 levels in

MVHR dwellings in

summer may indicate shift

toward natural vent during

warmer periods 0%

20%

40%

60%

80%

100%

MVHR Non-MVHR MVHR Non-MVHR MVHR Non-MVHR

February April August

Perc

enta

ge o

f m

on

ito

red

bed

roo

ms

Percentage ≤1000 ppm Percentage >1000, <1500 ppm Percentage ≥1500 ppm

Chart from Characteristics and performance of MVHR systems (meta study): MEARU/OISD/Four Walls

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CO2 – is not harmful

below 5000ppm, but it

can keep bad company.

CO2 is a useful indicator

for ventilation

effectiveness

Correlations can be found

with CO2 and chemical

pollutants

Formaldehyde is a

human carcinogen

CO2 concentration – a useful metric?

Chart with permission: MEARU

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0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 200 400 600 800 1000 1200 1400 1600 1800

mea

sure

d a

ir e

xch

ange

rat

e (a

ch)

measured TVOC (µg/m3)

Air exchange rates and TVOC concentrations in 30 bedrooms

Higher ach,

higher TVOC

=3Higher ach,

lower TVOC

=7

Lower ach,

higher TVOC

=14

Lower ach,

lower TVOC

=6

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0

1

2

3

4

5

6

7

8

9

10

0-10 10-20 20-30 30-40 40-50 50-60

NO2 (micrograms.m-3)

Dilution of combustion by-products

Data from DCLG 2009: Ventilation and IAQ in Part F 2006 homes study

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0

100

200

300

400

500

600

Bq

.m-3

Week

Radon (weekly mean)

Managing Radon – can we rely on ventilation?

≈ 0.5 ach

≈ <0.1 ach

≈ 0.5 ach

??

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Summary – Can we rely on good ventilation?

We know there are significant performance issues with domestic ventilation

installations.

But, moving some air is still better than allowing it to stagnate and become

polluted – particularly the more airtight the building.

Source control is important: building occupants have little or no control over

background levels related to construction materials.

Design for low emission is a priority

At <8 l/s/p source control becomes more important: AD F is based on ≈3.5 l/s/p

Moisture and bio-effluents are key pollutants in domestic environments

Can we rely on ventilation?…

Well, not entirely (at domestic rates). But we do need to ventilate, so it had better

be good!

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And finally…

Context is everything. E.g.:

What are you ventilating for – activities?

What is the building’s geometry/exposure/airtightness?

Is it in a Radon risk area?

How do (or will) occupants use the ventilation (including window use)?

What are the occupancy patterns and how does this relate to pollutants?

Risk relates to period of exposure and concentration of pollutant(s)

Etc., etc., etc.…

We don’t need to answer these to demonstrate Part F compliance. But we should

be asking when we determine appropriate ventilation strategies.

Ventilation should not be seen as an add-on – it is essential for safety.

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Thank you

ian@fourwalls-uk.com