Energy consumption of indoor grows is a delicate topic. Why? Because yields are a reflection of the energy being used! Efficiency is the keyword on this one.

Growing cannabis can be an expensive hobby. It’s often not the soil, fertilizers or seeds, hurting our wallets the most. It’s the annoying electricity bill we get every single month production is running. This article assumes that most of us are growing on a rather small scale in a home environment. We like to grow Cannabis because it’s the safest and best way when taking both legal-, and health risks into consideration.

The Paris Agreement, negotiated by the 2015 United Nations Climate Change Conference, had the key result of setting the goal of limiting global warming to less than two degrees Celsius. This can be considered as a big step in the right direction to save this wonderful blue planet we, our plants, and animals live on.

Cannabis growers are a few steps ahead of history; if it’s not us who care about the soils, the water and the air of our planet, who does? Not giving a shit is always an option, but it’s not the only one we have.

This article gives you some basic information on how to reduce your energy consumption when growing the best plant of all: Cannabis.


If you grow cannabis indoors, you probably already have the knowledge of a state-approved electrician. Knowing how to correctly wire all your growing equipment is basic knowledge. You can take things to the next level by buying a digital meter that measures all the things you need to know: Watts, amps, volts, KWHr, and other parameters.

The easier approach would be to visit a cannabis website that provides an online-calculator for your energy consumption. You can simply add your electrical growing devices and the amount of hours you use them, and it will calculate your costs.


1. Find the right size for your grow.

This is the by far the most effective way to reduce energy costs. You probably didn’t start to smoke cannabis two weeks ago, so it shouldn’t be a problem to roughly estimate the amount of bud you personally need per month. Here is a short example to get an idea of how to do this:

Let’s say a potential grower wants to consume about 30g of bud every month. Just one single autoflowering plant is easily capable of producing this amount of bud in an 8 weeks life cycle. This means a potential harvest of 120g after two months when growing just four small autoflowering plants. This is enough to last for about 4 months in this particular case. This hypothetical weed farmer could grow 2 months, take a break for 2 months, and then continue to grow again.

What has to be taken into consideration is that autoflowering varieties need a light cycle of 18/6, 20/4, or 24/0. This of course lowers their overall energy efficiency because “regular”, or “feminized” cannabis strains, only need 12 hours of artificial light when grown indoors. This article is not meant to open up a debate on the highly emotional topic of the “best” way to produce buds most efficiently. There are just too many factors in this equation.

The point is, to perfectly match the amount of energy, you put into your plants, with the amount of bud you need for your private purposes.

cannabis lights indoor growing

2. Think about your lighting solution.

The common lighting technologies are kind of problematic when looking at them from an efficiency point of view. These lamps have really high wattages between 250-1000W. This is not the problem at all. The amount of buds always correlates with the amount of energy you put into the “growing-equation”. But it depends a lot on how good the ratio between yield and energy is.

The gramm:watt ratio is something to start with. This ratio is not really ideal because it doesn’t necessarily consider the total amount of light hours being used. Longer flowering periods lead to a higher number of light hours you need to produce the desired quality.

The thing about these high pressure sodium lamps is that energy, you personally have paid for, gets converted into heat, which then has to be extracted, by using more energy you have to pay for. The heat can be quiet beneficial if you live in a colder region like Alaska, but often times it’s a bigger concern to get temperatures down, than up.

Sticking to the “old” lightning technology is logical because it has shown excellent results on numerous occasions. Thinking about new technology like LED lights though, can be a good option to lower your energy costs by still producing top-shelf buds.

LED’s emit lower heat and oftentimes have a light spectrum which is specifically tailored to plants needs. This means higher efficiency because less power is converted into heat, and into a light spectrum, the plant doesn’t fully appreciate. There will be a blog post on LED’s in the future to give you an overview about the technology and the recent developments in this field.

3. Install a controllable air system.

Most experienced growers will agree that it’s generally better to oversize the air system of an individual grow room, or tent. The reason for this is following: Let’s say you have the feeling that your cannabis plants perform best when they are being grown at a temperature of 26 °C. Your lamp emits a good amount of heat and it’s hot outside, maybe 30 °C. Your air system runs on full power to get the temperatures down. What happens if it’s 16 °C outside? Does your air system still need to run on full power? Most likely not! This is when you can turn it down and safe energy.

Installing an electric transformer that is able to reduce the voltage for your extracting tube vent is a smart move. If you have installed a transformer like this, you simply let your vent run on different velocities to safe energy when conditions allow this.

You can use a simple 5-level electric transformer that is normally used to regulate ceiling fans, they cost you a few bucks and are the cheaper alternative to the expensive ones from the grow shop. Beware of cheap “speed-controllers” or “dimmers” for your extracting tube vent, they tend to produce this annoying dimming-noise and are not suitable to any kind of silent grow operations.


• Think about the ideal size of your grow.

• Maybe change your conventional ballast for a digital one.

• Do your research about LED’s and make up your mind. They do work excellent!

• Save energy in the vegetation period by using “daylight” CFL’s, with a blue light spectrum, maybe in combination with some direct sunlight.

• Check if all the light in your tent is being used effectively. If not, think about new growing methods like SCROG (Screen of Green) or other techniques that lead to a homogeneous distribution of light to your plant(s).

• Run you air system on the velocity you actually need.

• Think of ways to switch between indoor and outdoor growing throughout the season.

• Don’t forget to have fun while optimizing. See growing as a hobby with multiple benefits. Becoming a skilled electrician is one of them.


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