The Project in Sierra Leone

The MEER project team has been working in Sierra Leone for over a year, experimenting with passive cooling techniques for underdeveloped settlements. Smaller scale experiments have shown that housing within Kroo Bay can be cooled by up to 7 degrees Celsius with the right adaptations. Currently, the team is working on developing a much larger project in the Aberdeen region of the capital city, which will focus on community scale cooling and the amplification effect.
Meer logo


In 2023, MEER started operating in Sierra Leone. The project aims to help people overcome extreme heat problems by applying surface reflectors to rooftops. MEER's scientific efforts are expected to significantly reduce urban heat, decrease freshwater evaporation, and assist agriculture to adapt.

Sierra Leone is a West African country which borders Guinea and Liberia. It has a wet tropical climate, high biodiversity, and diverse ecosystems. It covers an area of 71,740 sq km and is divided into 4 regions and 14 districts. The population is over 7 million, but it is one of the poorest countries globally, with high youth unemployment and significant rural poverty.

The MEER research program in Freetown is an experiment that is based on cooling data from a single dwellings. The research aims to answer the question of how effective and feasible it is to adapt to climate change in a neighborhood by using passive cooling techniques. This will be done by using an array of mirrors on the rooftops to reflect some of the incoming solar radiation, which would otherwise be absorbed as heat and cause temperature and moisture levels to rise.


Freetown is a city located near the equator, which means it has a constant and hot climate throughout the year. The temperature remains high during the day and night, with an average temperature of over 23°C. This makes it difficult to avoid the heat and its impact, as there are fewer opportunities to adjust work and life activities to avoid the heat. On average, the hottest days of the year are not particularly high compared to other cities in the study, but because of the consistent weather conditions, many more days lie just below this threshold. By 2050, climate change is expected to increase the number of extremely hot days to 120 days, or four months every year. The rapid urban development and migration have left Freetown with densely populated, underdeveloped areas with heat-intensifying surfaces, particularly around informal settlements such as Kroo Bay. MEER adaptation can help alleviate the heat island conditions and offer passive cooling technology to those who desperately require relief from thermal intolerance.


The MEER team selected Kroo Bay as a community to conduct indoor temperature measurements due to its tightly packed houses, with roofs almost touching each other, resulting in limited sunlight reaching the ground. Since most of the sunlight falls on the roofs, no significant heat is generated from the sides of the houses into the rooms. However, Kroo Bay is one of the marginalized communities that suffer from heat-related issues and disasters such as fire incidents. Hence, the MEER team organized a community engagement dialogue to introduce the Cooling Air Temperature Project and address these challenges. During the engagement, the team sensitized the community members, particularly children, about the negative impacts of heat on their well-being.

Despite the community's limited understanding of climate change, the MEER team enlisted the help of Mr. Mohamed, a community member proficient in the local language and familiar with the community, to overcome the language barrier and successfully impart the project goals and ideas. The team conducted a community survey to gather insights into the specific challenges faced by Kroo Bay residents due to excessive heat. Based on the survey findings, the team implemented measures such as Conformal mirror roofs, Flat mirror roofs, and white-painted mirror roofs to reduce heat absorption into homes. Although the project faced experimental phases due to fire incidents affecting some houses, the MEER team's efforts aimed to alleviate the heat-related burdens experienced by the community.


We recently conducted experiments in the Kroo Bay community to identify ways to minimize heat. During this time, we discovered that another community, Crab Town, was facing similar issues. We engaged in a dialogue with the community's chief and stakeholders, sharing insights about our organization and previous successful projects in Kroo Bay. The community expressed excitement about our proposed interventions.

Dr. Ye Tao, our founder, conducted a general engagement session with Crab Town's leaders and residents. He elaborated on the effects of heat on human society and the potential benefits of reflective roof installations. Unlike Kroo Bay, Crab Town showed promising potential for additional environmental projects.

After the session, we surveyed residents' homes to discuss heat-related challenges and explore waste management strategies. We also educated residents on waste reduction techniques, such as repurposing bottles into cups, to enhance their livelihoods while fostering environmental consciousness.

We are actively involving young people in Crab Town to participate in our upcoming surveys. We aim to empower them to become climate advocates within their community.

Scientific Planning in Crab Town

The Crab Town project is a large-scale initiative that aims to establish relationships between neighborhood-scale albedo and outdoor environmental conditions such as air temperatures, air circulation, and radiation environments. To achieve this, we are continuously measuring surface albedo, spatially-resolved outdoor air temperature, wind speeds, and direction logging at specific locations that could potentially signal atmospheric circulation emergence. We are also tracking street-level shortwave and longwave radiation, which is necessary for a comprehensive assessment of residential thermal comfort.

The project will use various environmental sensors, including outdoor and indoor air temperature and humidity sensors, weather stations with wind vane and anemometer, solar radiation sensors, albedometers, street-level visible radiation and thermal radiation sensors.

Crab Town Community was chosen for the trial based on its objective physical characteristics, such as large square area up to 6 hectares, uniform topography, uniform construction height consisting mostly of single-story buildings, moderate roof coverage ratio, slow surrounding land use changes, wide access lanes facilitating material transport, and a rectilinear street layout to facilitate grid sampling.

The instrumented region covers a square measuring 240 meters by 240 meters over a map of the Crab Town community. The air temperature sensors are positioned at varying heights (1 meter, 2 meters, and 4 meters) within a rectilinear grid spaced 20 meters apart.


To successfully carry out an experiment that alters air temperature at the neighborhood level, it is crucial to have precise temperature measurements ranging from 0.1 to 5 degrees Celsius. The absolute temperature scale is not important, but only the difference in temperature caused by the experiment. To ensure accuracy, all sensors used in the experiment were individually calibrated against a single reference sensor, specifically between 0 and 50 degrees Celsius. Furthermore, the sensor probe heads were cleaned weekly to prevent soiling. However, electronic drift may occur over time, which is why annual recalibration is necessary to test for its existence and amount. Plans for conducting these drift calibration experiments are currently being made.

When designing the sensor placement, the various microenvironments present in a densely populated urban residential community were taken into account. The aim of the study is to document and analyze the differences among these microenvironments and examine their overall change resulting from a global change in the neighborhood's albedo.

One of the major factors that can affect the measurement of air temperature in microenvironments is the interaction of the sensor probe with sunlight. To minimize the impact of sunlight, the probe surface is highly reflective, achieved by using glossy white paint and electroplated silver as current materials. Additionally, the probes are cleaned using water every week to reduce dust contamination. However, ongoing experiments, tests, and engineering are required to minimize bias resulting from sunlight.

Frequency of sensor data collectionand analysis

Data is collected on a monthly basis, while the analysis does not follow a regular schedule. Data officers inspect the raw data by visualizing a time-series plot and take note of any anomalies. The current process has revealed that approximately 20 out of 600 sensors display erroneous readings at times. So far, unreliable data points are easily distinguished from other data points and can be eliminated from the analysis in post-processing.

In regards to the deployment of sensors to measure the air temperature, it does not directly contribute to our understanding of climate patterns. The experiment conducted in the neighborhood is limited to small-scale measurements, which cannot provide insights into the larger climate system. The results of this experiment are likely to confirm what is already known with the climate models, which are too coarse-grained to provide insights into what happens within urban microenvironments.

Maintenance of large sensor networks requires significant resources. MEER is actively pursuing funding to enable long-term maintenance measures over several years and, hopefully, decades, to ensure the long-term sustainability and maintenance of the sensor network in Crab Town.

Long-term GOALS of the African project

Our organization is committed to inspiring communities to take responsibility for preserving and stabilizing the natural world and its ecosystems. We also aim to provide scalable solutions for heat adaptation and mitigation. To achieve this mission, we have set some goals for our current project and the organization as a whole, which are as follows:

We are currently collecting data from our sensor deployment in Crab Town. To combat the heat-related challenges faced by the community, we are implementing various roofing solutions such as conformal mirror roofs, flat mirror roofs, white-painted mirror roofs, and new zinc roofs. Additionally, we are conducting community empowerment workshops to educate and empower individuals while encouraging them to utilize waste materials like PET bottles for self-sufficiency and environmental progress.

Our focus is on sustainable material production, and we intend to achieve this by utilizing PET bottles and local materials. For example, we plan to use plastic to create solar cookers, furniture crafted from local sticks and PET bottle cordage, and brooms created from plastic bottles.

Looking towards the future, we plan to expand our organization beyond its current location and into other African countries. We want to extend our solutions to other places that are facing similar challenges related to heat. To achieve this, we are collaborating with the heat adaptation sector and forging partnerships with many organizations focused on heat adaptation in agriculture and related fields.

By aligning our goals with our vision, we aim to achieve tangible outcomes that contribute to our overarching goal of promoting sustainability and resilience in the face of climate challenges.

“Climate change is the single greatest threat to a sustainable future but, at the same time, addressing the climate challenge presents a golden opportunity to promote prosperity, security and a brighter future for all”

Ban Ki-Moon, Former Secretary-General of UN

Other Project