R&D brief - air conditioning and ventilation for hot humid climates¶

The brief for research into air conditioning and ventilation suited to hot humid climates, and the constraints it has to work within.

1. Objective¶

Develop a prototype air-conditioning (AC) unit optimised for high-temperature, high-humidity environments such as those found in parts of Tanzania and similar regions. The system should:

Cool indoor air effectively,
Remove excess humidity efficiently,
Introduce fresh outdoor air with minimal added energy load,
Operate reliably with minimal maintenance and energy input.

2. Core Design Challenge¶

In hot and humid climates, thermal comfort depends on both temperature reduction and moisture removal. Standard AC units often:

Overcool air to achieve dehumidification (wasting energy),
Or fail to adequately remove humidity (leading to discomfort and mould growth).

The design must balance cooling and dehumidification efficiently.

3. R&D Focus Areas¶

A. Cooling and Dehumidification Balance¶

Design for independent control of temperature (sensible load) and humidity (latent load).
Investigate two-stage cooling systems:
Stage 1: Moisture removal using cold coils or desiccant systems.
Stage 2: Reheat to deliver comfortable air temperature supply.
Use variable-speed fans and compressors for energy-efficient modulation.

Target Performance: - Indoor air temperature: 26–28°C - Relative humidity: 50–60% - Lower energy use than typical single-stage systems

B. Fresh Air Ventilation with Low Energy Penalty¶

Fresh air is essential for indoor air quality but increases the cooling and dehumidification load.

Ventilation Options: 1. Integrated into AC Unit: - Use heat and moisture recovery ventilators (HMRVs) or desiccant-based intake systems. 2. Separate Systems: - Trickle vents (possibly with moisture control features), - Stand-alone energy recovery ventilators (ERVs), - Solar-powered extract and intake fans.

Ventilation Target: - Supply 10–20 m³/h per person of fresh air - minimise additional cooling and moisture load

4. Context and Practical Constraints¶

Environmental Conditions: - Outdoor air: 30–35°C, 70–90% RH - Power supply: Intermittent or expensive - Maintenance: Should be low-frequency and simple - Noise: Quiet operation is preferred in domestic spaces

Materials and Build: - Corrosion-resistant components - Modular, repairable parts - Suitable for potential local assembly in East Africa

5. Outputs Required¶

Concept drawings and control schematics
Thermal and energy performance simulations
Bill of Materials (BOM) with approximate costing
Working prototype for field testing
Maintenance and installation guides suitable for non-specialist users

6. Success Criteria¶

Indoor climate: 26–28°C, 50–60% RH
Fresh air provision: 10–20 m³/h per person
Energy use: At least 30% less than conventional AC
Ease of use and maintenance
Robustness and reliability in local conditions

Source: ARC Technical Criteria - 725
Reference · confidence medium · Imported 2026-09-12, not yet reviewed · next review 2026-12-12
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Citation key: cooling-rd-brief