Air Tight Building Issues years ago Environmental Monitoring were asked to review the air quality within a new building just of the north circular in London. We went in with a blank sheet. No pre-conceptions of the how the house was constructed.

The owner had purchased the house for several million pounds but felt that it was not possible to occupy the house because there was and i quote “no air” in the house.

As part of the local authority building requirements, the building had to be designed to not only be airtight but also to have an active filtration system.

We provided the client with a full suite of monitoring equipment for hire including

Indoor air quality monitoring for :

Carbon Monoxide

Carbon Dioxide


Relative Humidity

Ambient Pressure

TVOC ( total volatile organic monitoring)

Particulate  aerosol sampling

Microbio sampling

Airflow monitoring

We also provided an independent review of the premises .

What was discovered –

Carbon Dioxide CO2 readings were typically around the 1500-1800ppm range

Relative humidity was 68-69%

Air flow was negligible

Ambient temperature was in the range of 23-25 , without any heating operating

internal ambient pressure was greater then external ambient.

Upon closer investigation, when we reviewed the filtration and air distribution system. The manual from the manufacturer stated that the ducting should be smooth bore rigid tubing. However the electricians that fitted the system used corrugated, flexible tubing. Upon removal it was found to be loaded with mould. The perfect distribution system.

To summarise . In trying to solve one problem. That of heat loss and heat inefficiency, it appears other problems have been created. Mould appeared in rooms without any explanation.

There were many problems, exacerbated by a poorly installed and not understood air filtration/ distribution system

Giving rise to :

  1. Poor Air Flow
  2. High Relative Humdity
  3. Mould Growth

The equipment used was a mixture of real time calibrated indoor air quality monitors . All the equipment was of a professional standard. Calibrated prior to the test it included :


Mini RAe 300 pid

Dusttrak DRX

MB2 Microbio sampler

Druck 750 pressure monitor

Kimo-instruments air flow

all supplied by Environmental Monitors it is important to note that modern home monitors tend to under report many of these issues. Each of our instruments cost several thousands of pounds and are regularly calibrated. That said we good observation and fresh air “rinsing” you can build a reasonable picture of your home environment using a cheap device

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