AI assistant & MCP

In-app assistant: the ✦ Assistant button in the builder opens a chat that reads your current design, modifies it, solves it, builds a room simulation and runs it against a real weather year — conversationally, in your language. Store your own AI provider key (assistant ⚙ → key settings) for unlimited chat billed to that account, or use the platform key, metered in compute tokens per message — the assistant panel shows the rate. The assistant is part of the paid plans; the MCP connector below stays open on every tier, the free one included.

MCP connector: HVAC Builder is an MCP server. In any AI agent that supports MCP connectors, add one with this URL — nothing to paste, sign in when it asks:

https://hvacbuilder.app/api/mcp

The connector registers itself, sends you here to approve it, and gets an access token scoped to your account. It works exactly as you do, with your tier's entitlements — and cannot approve further connections, change your plan, or reach admin tools. Disconnect it any time under avatar menu → Connections & API keys.

What it can reach: your saved systems, buildings and runs, the component and weather catalogs, and — if you are a supplier — your listings and RFQ leads. Tools that only read or compute are marked read-only, so a client can run them without asking each time; tools that write to your account are marked as such, and the few that update or delete a saved system, building or offering are marked destructive, so a client asks before each one.

One click: HVAC Builder is listed in the Claude connector directory — open the listing, press Connect, sign in and approve; the URL above is for every other MCP client. Before you connect you need an HVAC Builder account — the free tier is enough to design, solve and save; annual and building simulations need a paid tier or the example building's free daily runs. Things to try once connected: "Design a 12 kW R410A split for a 24 °C room at 35 °C outside and solve it" · "Fetch the TMY year for Lisbon and run my saved rooftop against it — how many hours does it fall short?" · "Load the Riverside Mall example, add a 200 m² office served by AHU-1, and simulate a week in July" · "Which catalog compressors on R454B cover 20–30 kW at 7 °C evaporating? Put the best COP one on my design" · for suppliers: "Fit AHRI 540 coefficients to this rating table and import it as a listing".

If something goes wrong: a connection that will not complete is usually a stale grant — disconnect it under avatar menu → Connections & API keys and add the connector again; a tool that answers with a code such as simulation or tokens is an entitlement of your tier, not a fault — the message names the plan or the top-up that lifts it; a solve that is refused names the component and the field it cannot solve with. Anything else: the Feedback link in the app header, or bugs@hvacbuilder.app. See the privacy policy for what is stored and for how long.

Without OAuth — scripts, CI, or a client that only takes a token — create an API key (same menu) and send it as Authorization: Bearer hvb_…, or as ?key=hvb_… for connector UIs that only take a URL. Keys work on the whole REST API too.

Ask for what you want in plain language — "add a heat-recovery core ahead of the coil and rerun the year on Helsinki", "save this as a rooftop and publish it", "simulate the mall with a 0.012 humidity ceiling on every room" — and the result lands in your account, ready to open. The complete tool list, with what each tool reads or writes, is in the MCP reference.