A better environment with idle free charging and heating

Three kids walking on a winter road

International studies show benefits from idle free charging and heating systems for air quality and the environment.

An increasing number of international studies reveal that cold starts are the leading cause of harmful emissions from vehicles. This is true even for the newest vehicles on the market. These emissions contribute to poor air quality, which can result in health issues. The good news is that the same studies show that electrical charging and heating are tools in reducing effects of a cold start.

One recent study on the effects of cold starts was performed by researchers at Berkeley, Carnegie Mellon, University of California and MIT. This study showed that modern gas cars release the same amount of harmful emissions in the first 30 seconds after a cold start as in 300 kilometers / 190 miles of driving with a warm engine.

Another test, performed by VTT – the independent state research institute of Finland, found that electrical heating can reduce harmful emissions by as much as 71% in cold conditions. (*Study conducted in Finland comparing cold start with vehicles preheated by WarmUp with app control)

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Furthermore, the Swedish Road and Transport Research Institute (VTI) concludes that significant cuts in emissions can be achieved through increased use of electrical preheating.

The consensus is the same in Norway, where both the Institute of Transport Economics (tøi) and the Norwegian Automobile Association (NAF) recommends the use of electrical preheating to lower emissions.

What is a cold start

Whenever an engine is started at temperatures below +10°C without prior heating, it is considered a cold start. Under these conditions, emissions will always be elevated, but they become progressively higher as temperatures get lower. A cold started engine will emit considerably more emissions at -10°C than at +10°C.

How cold starts lead to increased emissions:

To understand why the impact of cold starts is so significant, we must first understand its effects. The total increase in emissions after a cold start is a result of several factors. All these factors play an increasing role as the temperature gets lower.

  • The cold makes the oil too thick. The lack of proper lubrication leads to increased friction and a less efficient engine. This increases fuel consumption and emissions.
  • A cold engine is supplied with more fuel by design. This elevated consumption is maintained until the engine reaches its optimal operating temperature.
  • The catalyst must be warmed up to function properly. The catalyst removes harmful particles and gases from the exhaust, but it only works once the exhaust has reached its operating temperature. The increased infusion of fuel into a cold engine is partly designed to heat the catalyst more quickly.
  • The battery is drained in the cold and is recharged through additional fuel consumption. If you don’t charge the battery before you start driving, the alternator must recharge it while you drive. With cold weather, short drives, frequent use of comfort functions like defrosters, heated seats and steering wheels, the batteries in many vehicles are continuously drained and never fully recharged. A continuously running alternator leads to increased emissions.

How idle free charging and heating systems lower emissions:

An idle free charging and heating system consists of an engine heater, an interior heater, onboard smart charger and app control, all of which contribute to reducing emissions.

The engine heater heats the engine and/or oil, ensuring the engine is well lubricated, reducing friction and reaching operating temperature faster. This also results in faster warm air into the cabin.

The interior heater raises the temperature in the cabin contributing to reduced ice and snow accumulation on the windows. This reduces the need to use the vehicle’s heating functions.

The onboard smart charger charges the battery before you start driving. This means the battery can support the alternator in providing power to electrical comfort functions which results in less fuel consumption to run the alternator.

The use of the programmable control unit helps to optimize power consumption. The user can easily program the departure time ensuring the vehicle is warmer and ready when they need it. When using the auto function, the system automatically determines when to start heating based on the ambient temperature.

Massive reductions with idle free charging and heating system:

In the test performed by VTT in Finland vehicles with Euro 5 gas engines and Euro 6 diesel engines were tested against identical models outfitted with DEFA’s electrical charging and heating system, WarmUp. The test considered the first 20 minutes of driving after a cold start at -20°C. Some important findings are presented below:

GAS EURO 5 Co2 (g/km) PM (mg/km) NOx (g/km)
Cold start 306 152 0,35
Preheated 253 12 0,17
Reduction 17% 92% 52%


DIESEL EURO 6 Co2 (g/km) PM (mg/km) NOx (g/km)
Cold start 254 <1 0,97
Preheated 198 <1 0,60
Reduction 22% 0% 38%

Key findings:

  • An idle free charging and heating system can reduce the emissions of PM (Particle Matter) from gas vehicles up to 92%. PM is very harmful to health and a primary driver of poor air quality in the cities.
  • An idle free charging and heating system can reduce the emissions of NOx from gas vehicles by up to 52% and from diesel engines by up to 38%. The percentage-wise decrease was most substantial for gas engines but the effect in g/km will be more substantial for diesel engines (-37 g/km vs. -18 g/km). The reason is that they emit more NOx.
  • An idle free charging and heating system can reduce emissions of CO2 from gas engines by up to 17% and from diesel engines by up to 22%. The effect will be slightly more significant for diesel vehicles, even though they emit less CO2 (-56 g/km for diesel vs. -53 g/km for gas).
  • Also, preheating almost eliminates emissions of HC and CO.

All in all, the test shows that idle free charging and heating can reduce the total amount of harmful emissions by up to 71% and fuel consumption by up to 24% under the conditions tested.