Build and sell controllers to make any window fan a smart window fan. No one currently sells these. I need your help.


People use window fans to cool buildings when it is too hot inside and the outside temperature is cooler. This is a common occurrence because buildings are insulated and often contain people or machines(computers) generating heat. Using window fans this way has advantages over alternatives like air-conditioners. Fans are cheaper, quieter, and much more energy efficient.

However, using window fans effectively can be annoying. They need turned on and off based upon the relative temperature difference between the outside and inside air. They also need turned off when the inside air is below the temperature preference of the user. Doing this manually requires looking up the outside temperature or stepping outside. Typical situations where this can be particularly annoying is when fans are not easily accessible or the user is occupied when the fan needs turned on or off. One example is fans an attic or locked room in a business. Another is turning off fans early in the morning when many people are still asleep as the temperature warms or turning fans on in the early evening before a person is home from work.

A simple control device can be built to handle these problems automatically. An existing fan can simply be plugged into the device(that is itself plugged into a wall) instead of into the wall. This device can then read indoor temperature using a thermometer and outdoor temperature using the web. This enables it to turn on the fan only when the outside is cooler than the the indoor temperature and the indoor temperature is above the a minimum temperature set by the user.


It is estimated that there are over 200 million fans in the US not including ceiling fans. With 17-20 million sold per year. Some of these are desk fans but a large portion are window fans. These would be made more efficient and convenient with an intelligent controller. cite

Proof of concept

This is my current working prototype. It is controlling a fan automatically as described above. It is using a simple web based interface for configuration. Several changes need to made to make it cheaper to produce. But it is already good enought to sell.

It is build out of the following parts

Energy efficiency

Window fans are vastly more efficient than air-conditioners. A typical low power air-conditioner unit will consume over 500 watts of power while running. cite . Window fans typically use around 50 watts cite . Adding a temperature sensing controller to a window fan allows it to be run for shorter periods. Depending on the context it may run a couple of hours compared to leaving one on all night. Saving electricity is good for the consumer and the environment.

Business model and funding needs

The current prototype costs 53 dollars to build. Simple part substitutions bring that cost down to 43 dollars. I would like to build the final version for 30 dollars and sell it for 40-50. To bring costs down to this level requires an increase in part order sizes. Initially I would like to manufacture around 2000 devices. Additional costs will be advertising and design/sourcing work for a final product. Advertising for a device like this can be highly targeted both based on consumer location and search engine adword targeting. I expect to spend 1000 dollars on advertising. Finally designing a high quality final device that can be manufactured cheaply will require around 10000 dollars. However I am open to advice on these issues. In addition to the personal funding I am willing to put into the product I am looking for between a 50k and 100k investment. I have already written the software for the device.


Currently I am the only one working on this project. My name is Peter Lonjers. This is my first attempt to start a business but I have worked at 2 startups as a software developer. One of them became very successful. Take a look at my resume . Looking for investors that can provide advice and assistance with business side of the equation.


With adequate funding I should be possible to start selling at low volume by this summer. A few months will be needed for design and a few more for manufacturing. Because the device is small and the business has low continuing operating costs the consequences of missing that time-line are not severe. During the next winter it will be summer in the southern hemisphere.


Fortunately the basic ideas behind this device were patented long ago. These patents have now expired. The concept of using the web to get the outside temperature and allow for configuration can still be patented. It would additionally be prudent to get UL and FCC approval of the device. Although many similar products are sold without taking these steps.


Confirmation of the business model will be fast. After completing development the first step will be to sell the intial devices to get a good idea of the true market size. Steps after selling initial units will be to build the the device at lower cost and target it at wider markets especially outside the US were electricity prices can be more expensive. If the market is smaller than expected the devices can be easily stored to sell at a slower pace due to their small size. A further obvious expansion path is building a complete fan system. Finally the software and the components for the device can easily be re-purposed to be sold as generic smart plugs. Several of these types of devices are currently sold, however they are generally more expensive and complicated than the design used here.

Competition from the huge number of electronics suppliers is likely to cap the ultimate pay out of the model. However I expect the model to be able to get back multiples of the initial investment before this becomes an issue. However my primary goal is to get a product out there to help save our environment. Around 5% of energy use for households in the US is for cooling. This device would eliminate or reduce the need for air-conditioning for many people.


Email me at You can also call or text me at 559-288-5405. I am located in Los Angeles.