A monthly SiteBoosting study into how AI assistants recommend local businesses
Anyone considering a heat pump today increasingly skips Google — they ask ChatGPT, Claude or Gemini instead. But who do those AIs recommend, and where do they get their information? SiteBoosting measures it every month with the AI Findability Barometer. In September the spotlight was on one sector: heat pump installers. We asked the three biggest AI assistants the questions real consumers ask 135 times, across five cities, and analysed 1,014 cited sources.
The key findings
- AI relies heavily on platforms. With ChatGPT and Claude, over 40% of all cited sources come from trade portals, comparison sites and review platforms — not from installers’ own websites.
- One review platform dominates. Trustoo was cited 76 times for heat pump questions — more than twice as often as the runner-up, Werkspot (34 times).
- The three AIs differ enormously. Gemini backs every answer with almost 13 sources on average; ChatGPT and Claude cite 4 to 6 — and give no source at all in 22% and 31% of their answers respectively.
- Recommending without a source is common. ChatGPT and Claude regularly name specific companies without a single traceable citation. Consumers cannot check where the recommendation comes from — and businesses cannot influence why they are or are not mentioned.
How we measured
The barometer asks each AI fifteen realistic consumer questions about heat pump installers — from short search queries (“heat pump installer Amsterdam”) to full advice questions — spread across Amsterdam, Rotterdam, Utrecht, Eindhoven and Groningen. Each question was asked three times to ChatGPT, Claude and Gemini, always with live web search enabled: 135 measurements in total. For every answer we record which sources are cited and what type they belong to. We deliberately record no company names — only counts and source types. We repeat the same measurement every month, building a trend line. The full methodology is documented on our dedicated page: How the AI Findability Barometer works (in Dutch).
Where AI gets its recommendations
The breakdown of the 1,014 cited sources shows each AI has its own character:
| Source of citations | ChatGPT | Claude | Gemini |
|---|---|---|---|
| Installers’ own websites | 42% | 56% | 65% |
| Trade portals and comparison sites | 25% | 18% | 13% |
| Review platforms | 18% | 24% | 7% |
| News, government and information sites | 15% | 2% | 15% |
| Total sources cited | 255 | 184 | 575 |
Percentages per AI, all heat pump questions of September 2026 combined.
A company’s own website remains the largest category everywhere — if you don’t want to be found, don’t have a website. But with ChatGPT and Claude, more than four in ten references go through an intermediary: a portal, comparison site or review platform. Anyone missing there loses a large share of their AI visibility, however good their own site is.
The platforms that make the difference
Five platforms were cited most often for heat pump questions in September (all AIs combined): Trustoo (76×), Werkspot (34×), Slimster (26×), Warmtepompgids (17×) and Solvari (12×). Strikingly, it is precisely the platforms with reviews and comparison information that AIs use as reliable evidence. A well-maintained profile with recent reviews on these platforms is no longer a “nice to have” — it is direct fuel for AI recommendations.
Three AIs, three characters
Gemini behaves like a reference work: it cites sources for every question, almost thirteen per answer on average, and leans most heavily on individual company websites. ChatGPT and Claude behave more like an adviser: more compact answers, fewer sources — and in roughly a quarter to a third of answers no citation at all, even though specific companies are recommended. In around two out of three answers, the AIs name installers directly. For consumers this means: it pays to ask for sources. For installers it means visibility differs per AI — so you need to measure it per AI.
What does this mean for installers?
- Keep your own website in order. It remains the largest source across all three AIs — with clear service areas, up-to-date information and local pages per city or region.
- Claim and complete your profiles on the major platforms. Trustoo, Werkspot and Slimster are actively used as sources by AIs; recent reviews carry weight.
- Don’t count on a single AI. What ChatGPT recommends differs from what Gemini or Claude recommends — and the differences are bigger than between classic search engines.
- Measure it. AI findability can be measured and improved, just like classic SEO. Those who start now build a head start while everyone else is still thinking about Google.
About the AI Findability Barometer
The AI Findability Barometer is a monthly study by SiteBoosting. Each month we measure one sector in depth, alongside a fixed control set that tracks the trend across months. Next month: insulation companies. Want to know how visible your business is in ChatGPT, Claude and Gemini? Request the AI findability scan.
More about the method: How the AI Findability Barometer works (in Dutch)
