The back garden was only the first part of the answer.

I looked across the lawn and decided there was probably room for a ground-source heat pump. Then I looked at the narrow gate the equipment would have to get through. The garden had become a site, and the gate had become a question.

I wanted an initial feasibility assessment before choosing a loop type from an illustration. The size of the patch of grass was useful information, but it was not the whole design.

A closed loop circulates fluid through buried piping. Horizontal arrangements use trenches; vertical arrangements use drilled holes and can suit more restricted land. An open-loop system uses a water source directly and brings different water-supply and discharge questions.

Those are options to assess, not a menu where the smallest drawing wins. Soil and rock conditions, groundwater, heating and cooling loads, access and local requirements help determine what is feasible.

I collected the survey, available utility and well records, and plans for future work. I marked the septic area on the discussion copy and mentioned the addition we might build later. None of that replaced the professional checks or utility locates needed before excavation.

• How will drilling or excavation equipment reach the work area?
• Where are the boundaries, buried services, wells and septic components?
• What temporary space is needed for equipment and excavated material?
• How will the ground, access route and planting be restored?

NRCan's design guidance also ties the ground heat exchanger to the system's heating and cooling demand. I asked how the proposed loop would support that load over time. A rule based only on house floor area would leave too much unexplained.

Ontario requires an Environmental Compliance Approval, including a work plan, for vertical closed-loop systems extending more than five metres below ground. Its guidance allows a multi-site approval for installers; I asked how the proposed work would be covered. Other locations and loop types have different requirements.

The price comparison needed the indoor system too: heat distribution, electrical work, controls and any supplementary heat. I wanted drilling assumptions, exclusions and the process for unexpected ground conditions written clearly.

I also asked who would service the equipment and what records I would receive showing the installed loop. Buried work is much easier to understand while its location is still documented.

My lawn was still a possible place for the project. The useful result of the first visit would be a reasoned site assessment, with the access and approval questions answered before the garden changed.