Is Your Top Floor Too Hot?

Is Your Top Floor Too Hot?

Residents living on the top floor of the building face a considerable heating problem, particularly during scorching summers. Roof temperatures can rise to an unbearable 50°-60° Celsius which can make life pretty hard. There are often no signs of relief even during the nighttime, as the heat absorbed during the day re-radiates into living spaces.  

Despite opening the windows, the presence of heat in the roof slab re-radiates to the occupants directly causing discomfort. Prolonged exposure to such extreme heat can lead to health issues, including dehydration, heat exhaustion, and sleep disturbances.

With time, the grey color roof becomes black, the black-colored roof is known to yield substantial impacts on both surface and subsurface temperatures.

When sunlight hits a black roof
Source: Beating the heat: RMI

Graph 1 illustrates this phenomenon:

Where surface temperatures consistently exceed 40-50°C, while subsurface temperatures range between 30-35°C. Notably, a temperature differential of more than 10°C across the roof surface is evident, and this disparity subsequently propagates throughout the living space, contributing to more than 6-8°C differential in the internal temperature. Black roofs characterized by high solar absorptance, and low reflectance exhibit a propensity to absorb significant solar radiation, thereby resulting in high surface and interior temperatures. 

Graph 1 – Source: Cool Roofs for Cool Delhi: design manual.

While this challenge may appear daunting, it also offers a promising opportunity for positive change. The solution lies in the embracing of innovative and eco-conscious design. There are effective solutions to make the living space comfortable. Starting with insulation, is a vital step in preventing outdoor heat from invading your home. Reflective (white) color roof tiles act as a protective shield, reflecting sunlight and reducing heat absorption. The application of specialized reflective paint on the roof, deflects the sun rays and keeps the roof from becoming a heat trap. Additional ventilation and window treatments further enhance the top-floor oasis. These strategies can transform your top floor into a cool and pleasant retreat, even when the summer sun is at its fiercest. 

Graph 2 explains that the application of a cool roof coating to the roof assembly:


When sunlight hits a white roof
Source: Beating the heat: RMI

A noticeable reduction in temperature, both on the surface and sub-surface is evident, with decreases of 20°C and 5°C, respectively. The graph reveals that the temperature on the underside of the roof remains consistently below 30°C, which not only prevents the dissipation of heat into the interior livable spaces but, rather, contributes to the cooling of the indoor environment. Cool roofs have a well-documented capability to maintain temperatures 10 to 16°C lower than standard roofs when exposed to the intense heat of a summer sun. Cool roofs not only address energy levels but also improve the occupant’s comfort levels.

Graph 1 – Source: Cool Roofs for Cool Delhi: design manual.

Graph 3 Illustrates the reduction of electrical consumption using high-reflective roof paint.

Graph 3

Usage of reflective paint for the roof has a significant impact on energy savings.  From the graph, it can be observed that a considerable reduction of energy can be achieved by using reflective paint on the roof.

Painting light colors, laying white tiles, or having insulation for the roof helps moderate indoor temperature and maintain the comfort and health of the occupants.

McDBERL provides end-to-end MEP solutions and sustainable building services to ensure your building is cost-effective, offers lower operational costs, is highly energy and resource-efficient, and is extremely comfortable for the occupants.

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