このカフェは英語の使い方に注意した方が良い

The sign says:

× We are Economy OPEN
○ We are conserving electricity. Please come in!

• conserve energy 省エネをする、エネルギーを節約する (definition from Eijiro on the Web)

What they want to say is:

• It might look dark inside, but we actually are open. Don't worry! Please come in and have something to drink.

If I didn't understand a bit of Japanese, I think I would never have been able to figure out what this cafe was trying to say.

• figure out【句動】計算して合計［答え］を出す、算定する、〔答えを〕見つけ出す、 ～であると分かる、〔原因などを〕解き明かす、解明する、理解する、把握する、考え出す、考え付く、見当がつく  (definition from Eijiro on the Web)

It's a classic case of the noise in their English being too loud, making it not worth my time to even try to understand.

Conserving electricity is getting more important than ever. While it's great that utility companies are being forced to purchase electricity from enterprises generating electricity with renewable means, it may mean that we pay higher rates. Saving electricity could save you money.

• renewable energy 再生可能エネルギー  (definition from Eijiro on the Web)

I've tried to keep the AC off to conserve, but today it was a bit too hot in the afternoon. I turned on the AC for a few hours. Now I'm back to conserving, with the windows open.

In the afternoon, we are doing the same thing as this cafe at our classroom. The lights may be off, but there's a good chance that one of us is around. Why not send us email and come by for a visit? I'll even turn on the AC for you!