About ProEnergySaver and Y.W. Fung

Why I built this

ProEnergySaver started with an argument about a space heater. My electricity bill jumped by roughly a third one winter, and every online answer I found was either a vague article with no numbers or a calculator that demanded an email address before showing a result. I wanted one page that told me what a 1,500 W heater actually costs per hour on my own tariff, in under ten seconds, without signing up for anything.

So I built it, then kept going: twelve calculators covering heaters, air conditioners, refrigerators, dryers, washing machines, dishwashers, gaming PCs, televisions, water heaters, pool pumps and EV charging, plus a library of long-form guides that explain the arithmetic rather than hiding it. Everything uses the same visible formula, watts times hours divided by 1,000, multiplied by your rate per kWh, with fixed daily charges such as the UK standing charge shown separately instead of quietly folded in.

How it works, and what it never does

Every calculation runs 100% in your browser. There is no account, no sign-up, and no server that receives your appliance list, your tariff or your bill estimate. Nothing you type is uploaded, which is also why we can promise there is nothing of yours for us to lose or sell.

Default wattages and rates are cross-checked against Energy Star and US Department of Energy figures, Ofgem's price cap for the UK, and published residential tariffs from CLP Power in Hong Kong, Taipower and Japan's METI. Sources verified on 2026-09-19 and reviewed after each regulator update, and checked at least twice a year. Our editorial standards page documents the full verification process, and the privacy policy covers cookies and analytics.

Corrections and contact

If a figure here does not match your bill, tell me. Email hello@proenergysaver.app, replies within 48 hours. Estimates here are educational and are not utility advice; your own bill is always the authoritative source.

Last updated: 2026-09-19