ENTRY ID
IND-ENERGY-0001
Date added: 10/07/2026
Entry status: Draft
Submitted by: Jonathan Frost (Draft)
LLM: GPT-5.5
1. Solution Title
Build a Low-Cost Evaporative Fan Cooler
2. Step-by-Step Implementation Guide
Step 1 – Check Whether Conditions Are Suitable
Before building an evaporative cooler, check the weather forecast or a weather app for the relative humidity.
This solution works best when humidity is below about 60% and temperatures exceed 24°C. During humid weather the cooling effect is much smaller.
Completion: Weather conditions confirmed as suitable.
Step 2 – Gather Materials
Obtain:
- one desk, pedestal or box fan
- one shallow tray or washing-up bowl
- one large cotton towel, hessian cloth or cellulose evaporative pad
- approximately 2 litres of clean water
- a drying rack, clothes airer or simple frame to support the damp material
Estimated cost: £10–£40 using commonly available household items.
Completion: All materials assembled.
Step 3 – Assemble the Cooler
Fill the tray with approximately 2 cm of water.
Place one end of the towel into the water so that it continually draws water upward by capillary action.
Hang the damp section vertically on a clothes airer or frame.
Position the fan 30–60 cm away so that air passes through the damp material, not directly over the water.
Completion: Cooler assembled and operating safely.
Step 4 – Optimise the Room
Close curtains and blinds during the hottest part of the day.
Use the evaporative cooler near an open window or doorway where fresh air can replace humid indoor air.
Operate mainly during the afternoon and early evening while humidity remains relatively low.
Completion: Room prepared for efficient cooling.
Step 5 – Monitor Comfort
After 30–60 minutes, assess:
- personal comfort
- room temperature
- indoor humidity
- airflow
Adjust fan speed or ventilation if the room begins to feel damp.
Completion: Comfortable operating conditions established.
Step 6 – Maintain the System
Replace the water daily.
Wash towels or evaporative pads regularly to prevent mould and bacterial growth.
Allow materials to dry completely between prolonged periods of storage.
Inspect electrical equipment for safe operation around water.
Completion: System maintained safely.
Step 7 – Share the Knowledge
Demonstrate the cooler to neighbours, friends or community groups during hot weather.
Share photographs, instructions and measured performance to encourage wider adoption.
Completion: Knowledge transferred to others.
3. Polycrisis Strand(s)
Primary strand
Energy and Mineral Resources
Secondary strands
- Climate Change
- Food, Health and Disease
- Pollution, Toxics and Waste
- Inequality
Interaction effects
Reduces household electricity demand while improving resilience during heatwaves. Low-cost cooling methods particularly benefit households unable to afford conventional air conditioning.
4. Scale Category
| Scale | Primary | Enabling |
|---|---|---|
| Individual | ✓ | |
| Family / Household | ✓ | |
| Community / Village | ✓ | |
| City / Region | ||
| Nation State | ||
| Global |
Notes on scale interaction
The solution is implemented by individuals and households but can spread rapidly through community demonstration and local education programmes.
5. Dewey Decimal Classification
Primary DDC
697.9 — Heating, Ventilation and Air Conditioning
Secondary DDC
333.79 — Energy Conservation
644 — Household Management
363.738 — Climate Change
Subject headings
Passive cooling
Evaporative cooling
Household resilience
Heat adaptation
Appropriate technology
6. Regional Applicability
Evidenced implementations
India, Iran, Pakistan, Australia, Mexico, Spain, North Africa, southwestern United States.
Climatic / geographic scope
☐ Tropical
☑ Temperate
☑ Arid
☐ Arctic / Sub-arctic
☑ Coastal (during dry weather)
Political economy prerequisites
Requires only basic household equipment, electricity for a fan and access to clean water.
Contraindications
Not recommended as the primary cooling strategy where humidity consistently exceeds approximately 70%.
Care should be taken to avoid electrical hazards when operating fans near water.
7. Cost Estimate
| Cost Tier | Indicative Range | Basis |
|---|---|---|
| Individual DIY | £10–£40 | Household materials |
| Improved system | £40–£80 | Cellulose cooling pad and quality fan |
| Operating cost | <£1 per day | Fan electricity and water |
Cost notes
Most households already own a suitable fan, reducing costs further.
Water consumption typically ranges from 2–5 litres per day.
Funding mechanisms
Normally self-funded. Community groups or local authorities may provide demonstration kits for vulnerable households.
8. Timescale Estimate
Time to initial implementation
30–60 minutes.
Time to measurable impact
Immediately after assembly.
Time horizon of full benefit
Many years with routine maintenance.
Short-term vs long-term tension
Requires a small upfront investment of time and materials but can reduce summer electricity consumption and improve comfort during future heatwaves.
9. Evidence Base
Primary sources
- ASHRAE Handbook – HVAC Applications: Evaporative Cooling.
- University of Florida IFAS Extension – Fan and Pad Evaporative Cooling Systems.
- IPCC AR6 – Adaptation through passive and low-energy cooling.
- Traditional Persian Badgir and Indian Khus cooling systems documented in architectural and engineering literature.
Evidence quality
☑ Peer-reviewed
☑ Engineering standards
☑ Practitioner case studies
Known counter-evidence or limitations
Cooling performance depends strongly on ambient humidity.
Poor ventilation can increase indoor humidity, reducing comfort and increasing the risk of mould.
Evaporative cooling is not a replacement for refrigeration-based air conditioning in persistently hot and humid climates.
Supporting media
- Traditional Persian windcatcher examples.
- Indian khus cooling screens.
- DIY evaporative cooler construction guides.
- ASHRAE engineering diagrams.
Link verification date
10/07/2026
10. Implementation Indicators
Output indicators
- Evaporative cooler assembled.
- Household members trained in safe operation.
- Daily maintenance routine established.
Outcome indicators
- Reduced perceived indoor temperature.
- Lower electricity consumption compared with portable air conditioning.
- Improved comfort during hot weather.
Reporting mechanism
Individuals may record room temperature, humidity and electricity use before and after installation and share results with local community resilience groups or the GSTIA Open Library.
11. Related Entries
- Night-Time Natural Ventilation
- External Window Shading
- Reflective Window Films
- Cool Roof Paints
- Indoor Heatwave Preparedness
- Household Energy Conservation
- Passive Solar House Design
- Urban Tree Planting