I was having beers with my mate the other night. He runs an aircon and refrigeration business. Commercial stuff — big units, big contracts, big problems.

I asked him one question:

"If one product could revolutionize the fridgie/aircon space, what would it be?"

He didn't even hesitate.

A monitoring agent. A small device you bolt into a commercial aircon unit that reads pressure, temperature, fan operation, filter health — and reports it all back to your phone in real time.

No more sending a tech to site just to find out it's a dirty filter.

No more emergency callouts at 2am for something you could've diagnosed from the couch.

Here's the thing — he'd already scoped the whole project. Engineer calls. Hardware specs. Bill of materials. Corporate structure. He'd been sitting on this for two years.

The problem? His original approach priced out at $11,362 per unit.

Enterprise-grade BMS hardware. A $2,500 controller designed for skyscrapers, not rooftop package units. A $5,600 test rig. It was never going to work at that price point.

So the idea just… sat there.

Then I got involved.

He sent me every document he had. Four files. Spec sheets, engineering scopes, sensor requirements, the lot.

I know nothing about aircon. Couldn't tell you the difference between suction pressure and discharge pressure if my life depended on it.

But here's what I can do — I can feed everything to Claude and say: "I know nothing about this. Build me a product requirements doc. Find the cheapest path to market. Source the parts."

And that's exactly what I did.

The result?

Claude found a way to build the same device — same sensors, same monitoring capability — for ~$300 per unit.

That's a 97% cost reduction.

The trick was ditching the enterprise BMS controller entirely. An ESP32 microcontroller ($10), industrial pressure transducers ($45 each), waterproof temperature sensors ($4 each), and clip-on current sensors ($6 each). WiFi built in. MQTT for data. Cloud dashboard for monitoring.

Same job. Fraction of the price.

Within a week I had:

→ A full product requirements document → A revised bill of materials → The firmware architecture mapped out → A sourcing plan for every component → An AI diagnostic layer designed to catch common faults before a tech even gets in the van

The hardware is ordered. The code is written. We're meeting next week to put it all together.

Why does this matter beyond aircon?

Australia's HVAC services market is worth $13 billion. There are over 7,300 aircon businesses in the country. The global predictive maintenance market just crossed $14 billion and is growing at 30%+ per year.

And yet — there's no affordable, brand-agnostic retrofit monitoring device for independent HVAC companies servicing commercial units. The big manufacturers (Daikin, Carrier, Trane) all have cloud monitoring. But only for their own gear. If you're a fridgie working across ten different brands on fifty different sites? You've got nothing.

That's the gap.

The real product isn't the hardware.

It's the avoided truck roll.

Every unnecessary service call costs $150–250. If even 20% of dispatches could be diagnosed remotely first, the savings stack up fast. An AI agent that reads sensor data, matches it against known fault patterns, and texts the tech a diagnostic report before they even start the van?

That's not a nice-to-have. That's a business model.

Hardware + SaaS subscription + AI diagnostics. The playbook writes itself.

Here's what I keep coming back to.

My mate had the right idea two years ago. The market gap was real then and it's still real now. The only thing that's changed is the cost of building it.

The hardware got cheaper. The AI got smarter. And the gap between "I have an idea" and "I have a working prototype" collapsed from months to weeks.

He had the domain expertise. I had the build tools. That combination — deep industry knowledge plus someone who can ship fast — is the most underrated partnership in business right now.

We're meeting next week. I'll let you know how it goes.

— Daine

Got a mate with a problem in their industry? Sometimes the best products come from a conversation over beers. Hit reply and tell me about it.