Experimental and CFD studies on surface condensation

Condensation and mold problems have been identified as one of the severest IAQ problems in Japan. Especially in the wintertime, moisture condenses on cold wall surfaces where it can cause deterioration of the building materials and mold growth related to allergic symptoms. This paper discusses the possibility of using the CFD method to solve condensation problems.
Firstly, a CFD model for simulating condensation is developed, and then the validity of this model is examined experimentally.

A moisture control strategy that backfired

The use of humidistats to control air conditioners may create mold problems mainly in houses unoccupied for an extended period. This article looks for the best approach to control humidity in empty homes during hot and humid summers. Several solutions are proposed.

Toxic mold - a misnomer

An analysis of recently published research results is provided, showing that if molds and the different compounds they produce can lead to some health effects (allergies, infections, potential toxicologic effects) when inhalated, these effects occur only for exposures at very high doses. The potential toxicity from indoor air exposures is therefore very low, which allows to consider the term 'toxic mold' as a misnomer.

Measuring the efficacy of mold remediation on contaminated ductwork

Published guidelines on mold remediation do not specify sampling protocols to measure the efficacy of remediation efforts. The purpose of this study was to evaluate fungal remediation of contaminated ducts by comparing the amount of residual surface contamination to the amount in new ducts. Fungal contamination of galvanized metal and rigid fibrous glass ducts were evaluated using fluorometric and microscopic methods. Fungal contamination was measured in newly installed ducts in addition to pre- and post-remediation. Newly installed ducts had low levels of fungal debris.

Survival of bacterial and mould spores in air filter media.

The survival of bacterial and mould spores in new and used air filter media is explored. Samples of different media were challenged with specific microbial aerosols in a filtration test unit, and the viability of the microorganisms collected in the filter media examined. In five days there was no noticeable decrease or increase in the viability, nor did relative humidity have an influence.

Fungal colonization of air filters for use in heating, ventilating and air conditioning (HVAC) systems.

Describes how new and used cellulosic air filters for HVAC systems including those treated with antimicrobials were suspended in vessels with a range of relative humidities, and containing non-sterile potting soil to stimulate fungal growth. Prior to suspension in the chambers most filters yielded fungi, but only two of 14 non-treated filters demonstrated fungal colonization following use in HVAC systems. Antimicrobial-treated filters, in particular a phosphated amine complex showed a lot less fungal colonization than nontreated filters.

Allergies to moulds caused by fungal spores in air conditioning equipment.

Sensitizations to fungi that can be isolated when the fungi are removed from air conditioners are often shown by people suffering from various symptoms while in air conditioned rooms. It was shown that by using specific challenge tests fungal spores in air conditioners can give rise to allergic symptoms. The specific therapy prescribed for these reactions was hyposensitization. After this therapy, more that 70% of the patients could live and work again in air conditioned rooms without developing symptoms.

Fungal colonization of air filters and insulation in a multi-storey office building: production of volatile organics.

Describes a project to examine the secondary air filters in the air handling units on four floors of a multi-storey office building which had a history of fungal colonization of insulation in the air distribution system. Fungi were observed throughout the system. Lower concentrations of volatile organics were emitted from fungal affected air filter medium. Concludes that the growth of fungi in air distribution systems may affect the content of volatile organics in indoor air.

Fungal production of volatiles during growth on fiberglass.

In a laboratory chamber experiment, acoustic and thermal fibreglass insulation materials used in HVAC systems were colonized with fungi, which produced odour-giving volatiles. Suggests that these volatiles may be implicated in experience of indoor air quality and sick building syndrome symptoms.

Assessment of fungal (penicillium chrysogenum) growth on three HVAC duct materials.

Describes how laboratory experiments were conducted to assess the susceptibility of three types of ventilation duct materials to fungal growth. They were fibrous glass ductboard, galvanized steel, and insulated flexible duct. The results showed that only the flexible duct supported moderate growth of P. chrysogenum. The other duct materials showed no growth. Soiling with dust from residential heating and air conditioning systems increased the susceptibility of all three types, albeit at different levels of soiling, with the galvanized steel the least susceptible.