On Which Floor of a High-Rise Is the Heat More Bearable: Engineering Basics for Suffering City Dwellers

The question that thousands of renters and housing buyers ask themselves in the height of summer: is there a saving floor where the heat subsides? Real estate agents often repeat the mantra of the "golden mean" — floors 5 to 8, where there's a breeze and neither the ground nor the roof is too hot. But is that really true? Or is the choice of floor for comfortable heat endurance a lottery, depending on dozens of factors that real estate agents simply don't know about? Let's understand physically, not empirically, because our perception of heat in concrete jungles is governed by strict laws of thermophysics, construction mechanics, and urban climatology.

Physics of Urban Verticality: How a High-Rise Heats Up

To understand where the heat is perceived more easily, you first need to understand where it comes from in the building. Heat enters an apartment through three main channels: direct solar radiation through windows, heat transfer through outer walls and ceilings, and through ventilation when hot outdoor air enters through gaps and open windows. Each of these channels behaves differently at different heights.

Sunlight falls on a building at different angles throughout the day. The southern side receives the maximum insulation, the northern side — the minimum. But the most cunning is that upper floors, especially in buildings with flat roofs, experience additional heating from the ceiling. A dark bitumen roof can reach +70 degrees at noon, and this heat seeps into upper apartments both through reinforced concrete slabs and through ventilation shafts. On middle floors, this effect is smoothed out, and on lower floors, it is practically absent, but other mechanisms come into play.

Heated ground, asphalt, and courtyard areas emit long-wave thermal radiation, which is most felt in the first two floors. At the same time, fresh air, as we know, tends to rise, and by the 5-6th floor, it is less polluted and slightly cooler than at the sidewalk. However, this rule works during the day, but at night the picture may be reversed.

Night Flip-Flop: When the Top Becomes Hell and the Bottom Paradise

The classic mistake of many city dwellers is to assess thermal comfort only during the day. But the most torturous heat is sleepless nights. Here physics works against the upper floors. During the day, concrete walls and ceilings accumulate heat, heating through and through. By evening, when the sun sets, the upper part of the building continues to emit this accumulated heat into the rooms. At this time, if the temperature drops relatively on the street, it is compensated by the heat from the cooling roof and walls on the upper floors.

On lower floors, especially in buildings with basements, and also when there is shading from trees and adjacent buildings, night overheating is expressed less strongly. Moreover, the ground and foundation maintain a more stable, less fluctuating temperature. Therefore, in many cases, contrary to expectations, the first floors may turn out to be more bearable during periods of prolonged heatwaves when diurnal fluctuations reach 15-20 degrees.

Ventilation Effect: Where There's Wind, There's a Lifeline

Wind is one of the main allies of man in the fight against heat. The movement of air enhances sweat evaporation and carries away excess heat from surfaces. At an altitude of 20-30 meters (about 7-10 floors), the wind speed is usually higher than at the ground. Thanks to the absence of obstacles in the form of trees and low-rise buildings, middle and upper floors are ventilated better. However, this rule works only when windows are open and there is a draft. If you only have one window facing a courtyard well, then the wind effect is negligible, and you get all the delights of stagnant air, even on a high floor.

Moreover, on the open sunny side of a high floor, wind may not cool, but rather burn, if it brings heated air from adjacent concrete areas. The so-called "urban canyon effect" between skyscrapers creates complex turbulent flows in which cold and hot streams mix chaotically. Therefore, a specific apartment may be hot on the 15th floor, while the neighboring one on the same level may be cool, simply because the facade falls into the zone of an ascending thermal flow.

Material of Walls and Glazing: Concrete vs. Brick

You cannot consider the issue of floor height in isolation from the building's structure. Panel houses with thin outer walls have low thermal inertia — they heat up and cool down quickly. In them, upper floors turn into an oven by 11 am in the summer. In brick or monolithic houses with insulation, the thermal capacity of the walls is higher, and the temperature wave reaches the interior with a delay of 4-6 hours. In such buildings, upper floors can be quite bearable if the roof has good thermal insulation and a ventilated attic.

Also critical is the size of the windows and their orientation. If you have panoramic glazing on the southern side on the upper floor — congratulations, you've got your own greenhouse. At the same time, on the first floor with small windows facing a shaded garden, the heat will be felt significantly softer. Therefore, the statement "it's always better to take a middle floor" is an oversimplification that ignores architectural features.

South vs. North: Switching Places

If we are talking about the southern facade, then here height works against you: the higher, the more solar energy the walls and windows receive, as in the middle latitudes the sun is high at noon, and upper floors "collect" the maximum amount of direct rays. The northern facade, on the other hand, almost does not see direct sunlight, and there the main source of heat is the ceiling and air heated through the southern side. Therefore, on the northern side, upper floors may feel better than the first ones, due to greater ventilation and the absence of wall heating.

However, in southern regions where the sun is almost overhead, the difference between floors is leveled — rays fall on the roof and upper floors almost at a right angle. There it's hot for everyone, but the upper floors are especially hot. In northern cities where the sun is low, the vertical temperature gradient may even be negative: the ground is cold, and at an altitude of 100 meters the air may be significantly warmer. But this happens rarely.

Psychological Factor: The Illusion of Height

There is also a subjective perception. Psychologists note that a person on a high floor often overestimates the coolness from an open window simply because they see the horizon and feel "freedom". This state reduces anxiety and can make the heat less annoying. On the first floor, where the view ends at a fence or bushes, claustrophobia arises, which intensifies the feeling of heat. Therefore, sometimes the answer to the question of where it is easier lies not in the realm of physics, but in the realm of mood and habit.

Also important is the sound environment: on lower floors, the roar of traffic and air conditioners creates additional stress that exacerbates discomfort. On upper floors, it's quieter, and this helps to relax. However, if silence is combined with a hot ceiling and poor ventilation, then the win in silence turns into a loss in temperature.

What Do Measurements Say: Which Floors Are Objectively Hotter

Long-term observations in different cities give conflicting results, but common trends can be identified:

• In panel houses without roof insulation, the peak temperature falls on the last 2-3 floors, where the deviation from the average in the house may reach +5 degrees during the day and +3 degrees at night.
• In brick houses with a cold attic, the difference between the first and last floor during the day is 2-3 degrees, and at night up to 4 degrees in favor of the lower floors.
• In modern monolithic houses with a ventilated facade and insulated roof, the difference is almost imperceptible, and window orientation takes precedence.
• In buildings with underground parking under the entire building, the first floors receive additional cooling from the cold ground, and they can be significantly more comfortable in the summer.

Practical Recommendations for Choosing a Floor in Different Climatic Zones

If you live in a region with a dry hot climate (steppes, semi-deserts), where the temperature drops significantly at night, then upper floors with good ventilation may be preferable — you can ventilate and cool them in the evening. But if the nights remain muggy (southern coasts, humid subtropics), then choose lower floors or houses with massive walls and air conditioning.

In a temperate climate where heat comes in waves, floors 4 to 7 are considered optimal. Here there is no strong ground heating, there is no infernal roof heating, and the wind is felt. However, if you have a choice between the north side on the 15th floor and the south side on the 2nd, then the north side up top almost always wins in terms of heat.

It is also important to pay attention to the presence of trees in front of the windows. Large canopies, especially on the western and southern sides, can significantly reduce the thermal load on the first-three floors, making them cooler even compared to middle floors without shading.

Engineering Solutions as a Leveler

In recent years, architects and developers have actively introduced passive cooling systems: external blinds, green roofs and facades, and forced ventilation systems with heat recovery. In such buildings, the difference in temperature between floors is almost eliminated. Therefore, if you are buying an apartment in a modern residential complex of the "comfort +" class, then the floor for enduring heat becomes a minor parameter. Much more important will be the floor level for view characteristics and sound insulation.

But in old residential areas where everything depends on the thickness of the concrete and the condition of the roof, the question of the floor is crucial. There, the upper floor is almost always a guarantee of exhausting heat in July, unless you make a capital repair with the installation of a powerful air conditioner and additional insulation from the roof side.

Conclusion

There is no definitive answer to the question of which floor is better to bear the heat. Searching for the "ideal floor" in a concrete box is the same as searching for an eternal engine. In one house, it's comfortable on the seventh floor, in another — on the second. Everything depends on insulation, thermal properties of enclosing structures, wind regime, shading, type of roof, and even your personal psychological resilience. To summarize, in hot and humid regions, it is better to choose lower floors with shading, in dry regions — middle and upper floors with ventilation, in a temperate zone — a middle range (4-8 floors). But the main rule is not to trust real estate agents, but to conduct your own inspection: come to the apartment at the hottest noon, measure the temperature, open the windows, and assess the air movement. And remember that even in the hottest apartment, you can create an oasis of coolness with proper ventilation, window screening, and a rational ventilation schedule.
© library.ug

Permanent link to this publication: