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White Paper: Applications and Implications of Radiative Cooling in Dairy Farming

Dairy farming, a crucial component of global agriculture, faces a pressing challenge: heat stress in livestock. With an estimated loss of $1.5 billion annually for American dairy farmers, there is a dire need for sustainable solutions.

Coldrays’ white paper outlines how Passive Daytime Radiative Cooling (PDRC) roof technology can help keep cattle cool when the Arizona summer heats up. We’re excited to share our findings and potential solutions for reducing heat stress and improving milk yield and quality at Arizona’s 83 large dairy farms.

The Importance of Mitigating Heat Stress in Dairy Cows

Heat stress causes a sharp decrease in a dairy cow’s milk production, milk quality, fertility, and wellbeing. Even with heat mitigation, productivity losses from heat stress total to an estimated $1.5 billion annually for American dairy farmers. Traditional cooling methods like misting and mechanical ventilation are effective, but in the face of accelerating warming trends, the dairy industry is in need of innovative supplemental cooling solutions.

In dairy farming, the temperature humidity index (THI) is a commonly used metric to evaluate the risk of heat stress on lactating dairy cows. The table illustrates the varying levels of THI and the associate heat stress effects on dairy cows.

Heat StressNoneMildModerateSevere
THI heat stress values by Ignono, et. al

PDRC Represents a Compelling Supplemental Cooling Technology

Passive Daytime Radiative Cooling materials offer a sustainable and cost-effective approach to supplement existing heat stress mitigation techniques. This technology reflects solar radiation and emits thermal radiation from a dairy farm’s roofing, enabling cooling below ambient temperatures and a reduction of interior THI. This passive cooling method doesn’t rely on electricity or water, making it an environmentally friendly option that outperforms all other roofing materials.

Histogram comparing number of days at max THI for radiative cooling, cool roof paint, and galvanized roofing in each bin for the sample year in Casa Grande, AZ
Histogram of the number of days with max THI hour in each bin for the sample year in Casa Grande, AZ.

Our Results

A model of PDRC’s supplemental effects within Arizona’s dairy barns shows the technology has promise and makes economic sense. The technology is expected to increase annual milk production by an estimated 2.55% compared to standard barn roofing. In addition, expected increases in milk protein and fat content outpace the increase to total milk production, leading to higher value milk overall. These benefits not only enhance livestock comfort but also contribute to the economic viability and sustainability of dairy farms.

Roof TypeTotal Milk (kg)Fat (kg)Protein (kg)
Galvanized Steel9,303318297
Elastomeric Cool Roof9,497330306
Radi-Cool PDRC9,540332308
Annual expected total milk, fat, and protein measured in kilograms per head of cattle (total weight in kg)


The introduction of passive daytime radiative cooling roof membrane technology to dairy farming represents a significant step forward in addressing the challenges posed by heat stress. Its ability to improve livestock conditions, increase productivity, and reduce environmental impact makes it a promising solution for the future of dairy farming.

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Chris Hiller

Chris Hiller

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