Abstract
This 6-month controlled study evaluated dehumidifier effectiveness for mould prevention in 80 Singapore apartments. Properties were divided into intervention groups using various dehumidifier strategies and control groups without humidity intervention. Results showed apartments maintaining 55-65% relative humidity experienced 78% less mould development, with optimal cost-benefit ratio achieved at 6-8 hours daily operation.
Introduction
Singapore's ambient relative humidity frequently exceeds 80%, creating conditions highly favorable for mould growth. While dehumidifiers are commonly recommended for mould prevention, empirical evidence regarding their effectiveness in tropical residential settings has been limited.
This study aims to quantify the relationship between dehumidifier use, indoor humidity levels, and mould growth in Singapore apartments, providing evidence-based recommendations for homeowners.
Study Design
Participant Selection
80 HDB apartments in Tampines, Bedok, and Pasir Ris were selected based on similar construction age (10-15 years), floor level (5-15), and historical mould issues.
Study Groups
- Group A (n=20): 20L/day dehumidifier, 6-8 hours daily operation
- Group B (n=20): 20L/day dehumidifier, 12+ hours continuous operation
- Group C (n=20): 12L/day dehumidifier, 6-8 hours daily operation
- Group D (n=20): Control group, no dehumidifier intervention
Monitoring Protocol
Data loggers recorded temperature and humidity every 30 minutes. Monthly mould assessments were conducted using standardized visual inspection and air sampling protocols.
Results
Humidity Control
| Group | Avg. RH (%) | Target Days (%) | Mould Incidents |
|---|---|---|---|
| Group A | 58.2% | 87% | 3 |
| Group B | 52.1% | 94% | 2 |
| Group C | 64.7% | 62% | 7 |
| Group D | 78.4% | 0% | 14 |
Key Findings
- 78% reduction in mould incidents in Group A vs. Control
- Optimal humidity range: 55-65% relative humidity
- Diminishing returns below 55% RH with comfort trade-offs
- 6-8 hours operation sufficient for most apartments
Optimal Humidity Levels
Based on our analysis, we recommend maintaining indoor relative humidity between 55-65% for optimal mould prevention in Singapore homes. This range provides:
- Significant mould growth inhibition (78% reduction)
- Comfortable living conditions
- Reasonable energy costs
- Preservation of wood furniture and flooring
Cost-Benefit Analysis
Annual Operating Costs
- Group A (6-8 hours): $180-240/year
- Group B (12+ hours): $320-400/year
Potential Savings
- Average mould remediation cost: $800-3,000 per incident
- Estimated annual savings: $2,400 average (avoided remediation)
- Health-related savings: $800 per household (reduced medical visits)
ROI: 8-12x return on dehumidifier investment
Recommendations
- Dehumidifier Size: 20-25L/day for typical HDB flats (90-120 sqm)
- Operation Time: 6-8 hours daily, focusing on afternoon-evening periods
- Target Humidity: 55-65% relative humidity
- Placement: Central location with good airflow, away from walls
- Monsoon Season: Increase to 10-12 hours daily operation
Frequently Asked Questions
Do dehumidifiers really prevent mould growth?
Yes, our controlled study demonstrated that dehumidifiers significantly reduce mould growth. Apartments maintaining 55-65% relative humidity showed 78% less mould development compared to control groups.
What humidity level should I maintain to prevent mould?
Based on our research, maintaining indoor relative humidity between 55-65% provides optimal protection against mould growth in Singapore's climate.
What size dehumidifier do I need for my Singapore home?
For typical HDB flats (90-120 sqm), a 20-25L/day capacity dehumidifier is recommended. Larger condominiums or landed properties may require 30-40L/day capacity or multiple units.
How long should I run my dehumidifier daily?
Our study found that running dehumidifiers for 6-8 hours daily during peak humidity periods was most effective. During monsoon season, extended operation of 10-12 hours may be necessary.
Are dehumidifiers cost-effective for mould prevention?
Yes. Annual dehumidifier operating costs of $180-360 prevented an average of $2,400 in potential remediation costs, plus health-related savings of $800 per household annually.