[AC] 問﹕响做MVAC Design嗰陣，Indoor Air Quality IAQ 上有啲乜地方要注意？

答﹕

設計留意﹕

1. Outdoor Air Quality & Fresh Air Intake, 如唔好近停車場、垃圾站、Cooling Tower, screen cover prevent birds etc. ASHRAE 62.1 有指出離某類污染源既最小距離。

2. 要做到八成人滿意IAQ;

此外香港政府多個部門夾埋出過份"Guidance Notes for the Management of Indoor Air Quality in Offices and Public Places", 有個IAQ Certification Scheme (Voluntary), 分咗兩個Level, 分別係

Excellent Class - High Class, comfortable
Good Class - Protection to the public at large, including the Young & Elderly
依照下表控制到污染物响某個範圍，就可以攞到Cert.


3.  基於個地方大細、人數，計所需Fresh Air Flow Rate, 詳情見ASHRAE 62.1; Building Department都有要求

4. Humidity Control avoid mould; CO2 Sensor etc. control fulfill design criteria;

5. Maintenace要留意地方如容易積水發霉地方如Cooling Coil, Cooling Tower; Regular Duct Cleaning

此外，可選用以下Equipement提高Indoor Air Quality:

- Air Filters & Cleaners,

i) Particulate Filters, 尤其係High Efficiency Particulate Air (HEPA) Filter, 但Pressure Drop太大唔用得响Branch Duct;

ii) Electrostatic Precipitators, 但潮濕會影响發揮；原理係啲煙先經過一層帶有電子既Grid, 黐住電子後啲微粒變成負電荷，再由塊帶正電荷既Plate收集返；

iii) Gas Filter, 原理係直接吸收contaminating gas, e.g. Activated Carbons 活性炭；

iv) UV Lamp / Sterilizer

v) Photo Oxidation

上述兩溝，UV Lamp + Activated Carbons

vi)  Bio Oxygen Generator
原理係制造一系列electrons出嚟，經過既Oxygen就會變成帶負電，可以達到Particle Reduction & Sterilization效果 (報稱帶負電氧氣會互相黏埋一大舊，可黏住啲particle等佢可以重到跌落地板或Filter隔到；同埋可以阻止啲Mold繁殖)

vii) Chemical Air Scrubber

(鳴謝﹕Kelvin Mak, 紅豆; Source: Guidance Notes for the Management of Indoor Air Quality in Offices and Public Places, ASHRAE 62.1)