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Wellness IAQ Radon
10 September 2019

John Herbert, hong kong energy saving expert, BEAM expert
John Herbert

The latest Hong Kong guidance for Indoor Air Quality in public spaces was issued in Jan. 2019, it is almost identical to the 2003 version, with the majority of the parameters unchanged, except those highlighted in RED.

IAQ parametersIndoor Air quality parameters comparing 2019 v 2003 parameters click for larger image

The 8-hour sample time is still an issue, permitting "surrogate" sampling for a 4 hour sampling period, it also adds criteria for "INDOOR" Nitrogen Dioxide sampled over 1 hour, and somewhat logically Formaldehyde (HCHO) during 30 min sampling time.

However, critical measurements for human comfort, temperature, humidity and air velocity have been dropped, these were extensively used by BEAM practioners.

Considering measurement of the relative humidity is deleted, the guide refers to checking relative humidity, in the new visual mould inpsection included under the new latest version, so one could argue it includes humidity proxy.

The number of sample points in the 2019 version (page 7) remains unchanged. So overall there is little change in the 2019 version.

Radon (Rn)

Radon is a radioactive element with short half life, approx 3.8 days, typically a gas emanating from the rocks and soil beneath your feet and percolating through concrete into buildings and from certain building materials.

There is no safe level for Radon (Rn) yet there is no ready advice for handling Radon.

Following the IAQ guide its possible that a building owner will be paying for Radon (Rn) measurement on the 30th floor, presumably hedging against walls/floor off-gassing.

Underground, in basements and tunnels, the risk can be exacerbated when mechanical exhaust systems creating a (relative) negative pressure encouraging radon migration into the space from the soil, as shown in the sketch below. Good ventilation is always encouraged.

IAQ parameters radonRadon typically enters a building from the soil below larger view click image

Although the EPD IAQ 2019 guidance for indoor air quality states concentration for excellent class should not exceed 150 Bq/m3, the HKSAR ProPECC PN 1/99 states that:

"design, construction, or management of ventilation systems and buildings should aim to keep the radon levels in a building to a minimum, and not to exceed an annual average concentration of 100 Bq/m3."

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About the Author

John Herbert is a veteran chief engineer with more than 30 years international engineering experience, educated in the United Kingdom, he worked in the UK and then across Asia for more than two decades engaged by international and local companies. He is a Hong Kong Registered Energy Assessor (REA) and BEAM Professional, and is stationed in Hong Kong.


tags: iaq, radon,comfort, Hong Kong, indoor air quality
date: 30-05-20
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