PREVENTION OF MOULD GROWTH IN BUILDINGSBy : YM Raja Ismail bin Uda

1. Air Conditioning Definition From ASHRAE

2. Definition of Thermal Comfort

3. Definition of Mould

4. Factors Contributing To Mould Growth

5. Problems Of Moisture Intrusion

6. Architectural Considerations

7. Mechanical Considerations

8. Structural Considerations

9. Building Operation and Maintenance Stage

10.Corrective Plans and Corrective Measures

11.Conclusions

AIRCONDITIONING DEFINITION - ( ASHRAE )

The purpose of a heating, ventilation and Airconditioning (HVAC) system are to help maintain good indoor air quality through adequate ventilation with filtration and provide thermal comfort :-

To maintain a suitable degree of humidity – RH To supply a constant and adequate supply of

ventilation – Fresh air & air movement To efficiently remove the air from all micro-

organisms, dust and other foreign bodies – IAQ / CO2

To efficiently cold the air of the rooms – Room temperature

DEFINITION OF THERMAL COMFORT – ( ASHRAE )

As the state of mind in humans that express satisfaction with surrounding environmental (ASHRAE STANDARD 55)

◦ The thermal comfort is maintained when the heat generated by human metabolism is allowed to dissipate, thus maintaining thermal equilibrium with the surroundings. It has been long recognized that the sensation of feeling hot or cold is not just dependent on air temperature alone.

THERMAL COMFORT VARIABLE

Room dry bulb temperature – T Relative humidity – RH Fresh air ventilation – FAV Air movement – V Air change – AC Supply air volume – SAV Total cooling capacity – TCC Indoor Air quality – CO2 Noise level - NL

RH

T

AC

V

TCC

SAV

TEMPERATURE & HUMIDITY RANGES FOR COMFORT

CONDITIONS RELATIVE HUMIDITY (%)

ACCEPTABLE OPERATING TEMPERATURE ( ° C )

SUMMER ( Light Clothing )

If 30%, thenIf 60%, then

24.5 - 2823 - 25.5

WINTER ( Warm Clothing )

If 30%, thenIf 60%, then

20.5 – 25.5 20- 24

SOURCE: ASHRAE 55 -2010

JKR SPECIFICATION AND GUIDELINE

SOURCE : MS 1525:2009

a. Recommended design dry bulb temperature 23°C – 26°C

b. Minimum dry bulb temperature 22°C

c. Recommended design relative humidity 55% - 70%

d. Recommended air movement 0.15 m/s – 0.5 m/s

e. Maximum air movement 0.7 m/s

f. Recommended outdoor design condition- Dry bulb- Wet bulb

33.3°C27.2°C

RECOMMENDED COMFORT VARIABLES AND PREVENTION OD MOULD GROWTH

1. Room temp. 24

2. Relative humidity 60% - 70%

3. Fresh Air Ventilation 15-20 cfm/person

4. Air movement 0.5 m/s

5. Air change 6-10 Ac/hr

6. Indoor Air Quality – CO2 < 1000 ppm

7. Supply air volume - SAV 1.10% of design SAV

8. Total Cooling Capacity - TCC 1.10% of design TCC

9. Noise level - NL Below acceptable Level

DEFINITION OF MOULD

There are thousands of known species of moulds, which include opportunistic pathogens, exclusive saprotrophs, aquatic species and thermophiles. Like all fungi, moulds derive energy not through photosynthesis but from the organic matter on which they live. Typically, moulds secrete hydrolytic enzymes from predominantly hyphal tips. These enzymes degrade complex biopolymers such as starch, cellulose and lignin into simpler substances which can enter the hyphae. In this way, moulds play a major role in causing decomposition of organic material, enabling the recycling of nutrients throughout ecosystems. Many moulds also secrete mycotoxins which, together with hydrolytic enzymes, inhibit the growth of competing micro-organisms.

– Source Guidelines On The Prevention Of Mould Growth In Buildings JKR Malaysia 2009

FACTORS CONTRIBUTING TO MOULD GROWTH

MOULDS

RELATIVE HUMIDITY ABOVE 70%

SPORES OXYGEN

TEMPERATURE ( 5 TO 50° C )NUTRIENT

PROBLEMS OF MOISTURE INTRUSION Examples and Pictures)

Design Or Construction FlawsSelection of wrong materials for a building component, installation of damaged materials, improper sizing of the air-conditioning & ventilation system and other design flaws can lead to a wide range of conditions that can contribute to mould growth.

Building Component Or System FailureA window or wall structure, or other component may be defective or improperly installed, allowing moisture to intrude.

Operational FailureBuilding equipment may not be operated in accordance with the design parameters, resulting in leaks, condensation or flooding and home mould growth.

Building ChangeSpace may be reconfigured; major equipment may be replaced; tenants may add specialized equipment. Any of these changes can compromise the ability of the building to shed moisture. Therefore, it is critical to establish procedures that prevent moisture intrusion and mould manifestation.

ARCHITECTURAL CONSIDERATIONS

ARCHITECTURAL CONSIDERATIONS

24 HRS ROOM & NON-AIRCOND AREA

ARCHITECTURAL CONSIDERATIONS

CONDENSATION ON SLAB

MECHANICAL CONSIDERATIONS (Examples and Pictures)

Design StageConstruction StageTesting, Balancing & Commissioning Stage

DESIGN STAGE

Insulation

Pre-Insulation Pipe

Internal Duct Insulation

Drain/Condensate Piep Insulation

Heat Load

Exhaust Duct

Location Supply Diffuser

Pipe Routing

Accesibility

System Selection

Building Operation Load

Adequate airchange

Location Fresh Air Intake

Prevent oversize proposed by contractor

Construction Stage

Equipment Selection

Proper Duct Installation

Approved Sealant

Drain pan gradient

Control Valve

Collar Joint

Excessive Infiltration

Testing & Balancing

SELECTION MATERIAL

CONSTRUCTION (MECH)

STRUCTURAL CONSIDERATIONS

Design

• Quality of structural member

• Corrosion prevention

• Flat roofConstructi

on

• Water tight floor

• Sanitary fitting installation

• Application of Damp proof course & membrane

• Water proofing materials

• Dry structural element

• Avoid water leakage

• Site cleaning

STRUCTURAL

BUILDING OPERATION AND MAINTENANCE STAGE

(Examples and Pictures)

OPERATION

REPAIR WORKS BY COMPETENT PERSON

HVAC MONITORINGCONTR

OL SYSTEM

VENTILATION

VENT FOR MOISTURE SORCEEliminatPeriodic

Maintenancee The Spores

Access For

Maintenance

Removal of

Unwanted Materials

Room Temperature

MechanicRoutine

Assessmental Maintenance

Works

Mould Growth Monitori

ng

Attend To Moisture

ImmediatWindows & Doorsely

Water Seepa

ge

RENOVATION

WORKS

OUTSIDE AIR

INFILTRATION

QUALITY OF CHILLED /

CONDENSER WATER

CLEAN/REPLACE

AIR FILTER

CORRECTIVE PLANS AND CORRECTIVE MEASURES

CONCLUSIONS

THANK YOU…

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