Parked cars make cities hotter. Parking lots are covered in concrete and asphalt, which soak up heat all day. When the sun goes down, that heat stays in the air, making cities much warmer than areas with more trees and grass. This is called the urban heat island effect, and it makes summers feel even hotter. Cars sitting in the sun also heat up, releasing more warmth into the air around them.
Some things can help reduce this heat. Light-colored cars absorb less heat than dark ones, and parking in the shade keeps cars cooler. Simple car covers can also help by blocking sunlight and keeping the inside of a car from getting too hot. But the biggest problem is not just one car—it is the thousands of cars sitting in hot parking lots every day.
Hotter cities mean worse air, higher electricity bills, and more discomfort for people. Simple changes, like adding trees, using cooler pavement, and building better parking areas, can make a difference. Learning about the problem is the first step—now it is time to find ways to fix it.
How Parking Lots Trap the High Temperature
Parking lots contribute to the urban heat island (UHI) effect by absorbing and holding heat throughout the day.
Asphalt and concrete surfaces, commonly used in parking areas, have low reflectivity and high-temperature retention, making cities significantly warmer than surrounding rural areas.
Even after sunset, these surfaces continue to radiate heat, keeping urban temperatures high.
Why Asphalt and Concrete Make Parking Lots Hotter
- Low Albedo Effect: Dark surfaces like asphalt absorb up to 95% of solar radiation, reflecting very little sunlight.
- Heat Retention: Concrete and asphalt store temperature during the day and release it slowly at night, prolonging warmth in the environment.
- Surface Temperature Differences: Studies show asphalt can reach 150–170°F in direct sunlight, while shaded or grassy areas remain much cooler.
Why Parking Lots Stay Hot Even at Night
The high temperature absorbed by parking lots during the day does not disappear when the sun goes down. Instead, the pavement slowly releases it back into the air, keeping temperatures high long into the night.
Without trees or vegetation to provide cooling through shade or moisture evaporation, parking lots act as sources even in the evening.
Buildings and roads surrounding parking lots make the problem worse. The temperature stored in pavement and walls radiate outward, creating pockets of warm air that remain trapped between structures.
This effect is strongest in dense urban areas, where tall buildings and large paved spaces prevent high temperatures from escaping.
Cities with few green spaces experience nighttime temperatures that are 7–10°F higher than rural areas, increasing energy demand as people rely on air conditioning to stay cool.
Shade and Trees Can Make a Difference
Large paved areas absorb heat all day, making cities much warmer than surrounding regions. Without shade, surfaces store temperature and release it slowly, keeping temperatures high long after sunset.
Greenery plays a crucial role in cooling down urban spaces by providing natural cover and lowering ground temperatures.
How Trees and Shade Reduce Heat
- Blocking Direct Sunlight: Canopies prevent sunlight from reaching pavement, lowering surface temperatures by 20–45°F.
- Cooling Through Evapotranspiration: Trees release moisture into the air, creating a cooling effect similar to sweat on human skin.
- Improving Air Circulation: Vegetation helps disperse heat, preventing it from getting trapped in dense urban spaces.
- Lower Cooling Costs: Shaded areas reduce energy use by decreasing the need for air conditioning.
- Better Air Quality: Trees absorb pollutants, improving the air people breathe.
- More Comfortable Public Spaces: Cooler streets and sidewalks make cities more walkable and enjoyable.
Better Pavements Can Lower the Temperature
Most surfaces in urban areas are made from materials designed for durability, not heat control. Dark asphalt absorbs nearly all sunlight, causing temperatures to rise dramatically during the day. Even at night, these surfaces release it slowly, keeping streets and sidewalks much warmer than natural ground.
Unlike shaded or grassy areas, solid pavement lacks the ability to release moisture, which is a key factor in natural cooling. Without water absorption, the heat remains trapped, contributing to the urban heat island effect. The hotter the surface, the more energy is needed to cool buildings, increasing electricity demand.
How Different Materials Affect Temperature
- Cool Pavements Reflect More Sunlight: Light-colored or specially coated surfaces reflect up to 50% more sunlight, keeping them significantly cooler.
- Permeable Surfaces Absorb Less Heat: Materials like porous concrete or stone pavers allow water to pass through, which helps cool the ground.
- Grass and Gravel Alternatives Provide Natural Cooling: Using grass-filled grids or gravel instead of solid pavement prevents extreme heat buildup.
Smarter Parking Designs Can Fix the Problem
Efficient use of space matters just as much as materials. Parking areas designed with unnecessary empty lanes or oversized sections add more heat-absorbing surfaces.
Instead of spreading outward, modern designs focus on maximizing capacity while minimizing the ground area affected by heat.
How Layout and Design Affect the Temperature
- Reducing Unnecessary Pavement: Compact designs limit excessive paving, leaving more space for trees and green areas.
- Adding Shade Structures: Carports, solar panel canopies, and trellises provide relief from direct sunlight.
- Using Multi-Level or Underground Options: Moving vehicle storage above or below ground reduces surface heat absorption.
FAQs
The Bottom Line
Unshaded parking lots, heat-absorbing pavement, and parked cars all contribute to rising temperatures in cities.
Without proper design and materials, these spaces become heat traps, making urban areas hotter during the day and slow to cool at night.
Simple changes, such as planting more trees, using better pavement materials, and designing smarter layouts, can help reduce the impact. Cities and individuals both have a role to play in addressing this issue.
Cooling down urban spaces starts with better choices—small improvements today can lead to a more comfortable and livable future.