With sweltering temperatures and humidity levels that make even shade uncomfortable, it's no wonder Israelis are spending up to NIS 8,000 for new air conditioning systems. Israelis are expected to purchase 180,000 new air conditioning units this summer, according to the Manufacturers Association of Israel, a 45 percent jump over last year's numbers. The rising number of air conditioner sales is due to many factors, said Yagil White, managing director of air conditioning at the Electra Group. Israel's consistent prosperity is perhaps the main one, he said, but the summers have continuously been hotter than past ones, and as new apartments are now bigger, more machines are needed to keep them cool. The price of new systems has also fallen, but only slightly, White said. The average household in Israel now has two air conditioners, up from 1.8 in 2006, when manufacturers sold 120,000 new machines, according to the association. According to Ze'ev Krool, manager of Arie Krool Industries Inc., customers are buying more efficient models. With high energy prices, they're even willing to pay more for "green" machines, he said. Electra, an Israeli air conditioner manufacturer, designs much of its new products to be green-friendly, White said. Electra brought the inverter system to its air conditioners. The system, which was pioneered in Europe, has only made its way to Israel in the last couple of years. To save energy, an inverter lowers its power consumption to 10% after cooling a room, unlike traditional models, which simply turn off. When the room needs to be cooled again, the machine automatically returns to normal output. The inverters save energy because the machine is always on. A large percentage of consumption is used when starting up, so traditional machines consume more power every time they turn on again. Though more expensive, the ones that have inverters are growing in popularity. Krool said 10% of his customers have started to purchase air conditioners with inverters. Krool said customers are also buying more portable air conditioners, which are also more efficient. The portable device pushes one horsepower, while stationary devices often push more; they can fit in the backseat of a car, so people can bring them from home to work, he added.