Cabin air temperature of parked vehicles in summer conditions: life-threatening environment for children and pets calculated by a dynamic model

Abstract

In vehicles that are parked, no ventilation and/or air conditioning takes place. If a vehicle is exposed to direct solar radiation, an immediate temperature rise occurs. The high cabin air temperature can threaten children and animals that are left unattended in vehicles. In the USA, lethal heat strokes cause a mean death rate of 37 children per year. In addition, temperature-sensitive goods (e.g. drugs in ambulances and veterinary vehicles) can be adversely affected by high temperatures. To calculate the rise of the cabin air temperature, a dynamic model was developed that is driven by only three parameters, available at standard meteorological stations: air temperature, global radiation and wind velocity. The transition from the initial temperature to the constant equilibrium temperature depends strongly on the configuration of the vehicle, more specifically on insulation, window area and transmission of the glass, as well as on the meteorological conditions. The comparison of the model with empirical data showed good agreement. The model output can be applied to assess the heat load of children and animals as well as temperature-sensitive goods, which are transported and/or stored in a vehicle.

Evaluating the impact of solar radiation on pediatric heat balance within enclosed, hot vehicles

“…The heating rates in sun-exposed vehicles ranged from an average of 0.30°C min −1 for the minivan to 0.42 °C min −1 for the economy car, which is largely due to the relative air volumes in the vehicles; however, similar equilibria are reached. These conditions are similar to those found by atmospheric models estimating in-vehicle steady-state conditions [ 11 ].…”

“…From this estimation, we can assess the accumulation of heat (see example in Table 2 ) based on the energy balance ( Equation 1 ). Estimates of the T c up to 50 and 60 minutes are determined based on the amount of data collected ( Table 1 ) and the time range at which in-vehicle conditions generally reach a steady-state across the vehicles, as also found by Horak et al [ 11 ]…”

“…Lethal in-vehicle temperatures are also reached on cloudy days, even though ambient air temperatures can be up to 10°C less when compared to sunny days [ 10 ]. In direct solar radiation, a greenhouse situation occurs within the vehicle, trapping longwave radiation and heating the vehicle interior to a steady-state with little-to-no airflow [ 11 ]. This situation of radiation trapping highlights the importance of solar exposure in vehicle heating and child vulnerability [ 12 , 13 ], even on milder days [ 14 ].…”

The characteristics of heat inside a parked car as energy source for thermoelectric generators

“…This experiment showed the same results as Grundstein's experiments [21]. The temperature in the driver seat (T3) also rose up to 45°, and this heat could be dangerous to humans and the other objects inside the car as mentioned by Horak [18]. The temperature under the car (T4) was stable and almost the same as the ambient one (T5).…”

“…According to Othoman et al [15], an increase in the car cabin's temperature due to solar heat could reach 60% higher than the ambient temperature. Other researchers, among others, Horak, Grundstein, Guard, and Al-Kayiem [16][17][18][19][20], also stated that a high temperature rise in the cabin can be harmful for humans and can be dangerous for sensitive objects inside the car. Even if the car is parked for less than 60 min, it is still really dangerous and may take lives of humans or animals inside the car.…”