1. Why the energy class does not replace a survey
Three reasons, and the third is decisive. The class is an aggregate indicator that does not show how the losses are distributed. The class does not measure the condition of the structures, which may be a problem independently of energy. And the class does not show moisture damage, which is the most expensive surprise in renovation.
Insulating a damp structure makes matters worse rather than better. A survey is therefore not an extra cost before a renovation but a condition of it.
2. What to survey
Five areas, all of which may change the design, and the fourth is the most often underrated. It concerns the ventilation.
| Area | Content |
|---|---|
| Load-bearing structures | foundation, walls, panel connections |
| Moisture and its sources | from the ground and from internal condensation |
| The roof | its watertightness |
| Building services | heating, ventilation, water and electricity |
| The condition of facade fixings | a separate subject in panel buildings |
Renewing the ventilation is invisible work whose effect on the indoor climate is greater than that of replacing the windows, and that is precisely why it is the most often left out of the discussion. Residents notice it immediately.
3. In what order
Three steps whose order is logical, and the second is often skipped. It concerns commissioning the surveys.
A visual inspection and the gathering of existing documents. Targeted surveys where the inspection points to a problem. And only then the energy calculation and the design.
The second is skipped because it costs money before anything visible happens. A targeted survey is meanwhile cheaper than a full one and more accurate than a guess.
4. Why a survey costs less than its absence
Three mechanisms, all concerning surprises. A surprise during construction is more expensive than the same work planned, because it interrupts the programme and is priced without competition. A surprise may require the design to be changed, which affects all the remaining work. And a surprise in an occupied building also means disturbance to the residents, as covered by the article on living in the building during works.
The mechanism of unforeseen circumstances is covered by the article on forecasting the cost. A survey does not eliminate surprises entirely: it reduces their number and moves some of them into the planning phase, where they are cheaper.
5. What a survey must deliver
Four things to require of the result, and the fourth is required least often. It concerns the limits of the survey.
| What to require | Why |
|---|---|
| A description of what is there | not only of what is wrong |
| The problems ranked by severity | it makes deciding possible |
| Recommendations by particular structure | it ties them to the design |
| A note on what was not surveyed and why | it states the limits of the survey |
A survey that does not state its limits leaves the impression that everything was checked, and it is that impression which leads to later surprises.
Summary and four practical rules
The energy class does not replace a survey, because it is an aggregate indicator that does not measure structures or show moisture damage, and insulating a damp structure makes matters worse. Five areas must be surveyed, of which ventilation is the most underrated even though its effect on the indoor climate is greater than that of replacing windows. A survey does not eliminate surprises but moves some of them into the planning phase, where they are cheaper than during construction priced without competition.
Four rules: commission the survey before the design, not after. Check for moisture before planning insulation. Require the survey to state its own limits. Treat ventilation separately, since its effect on the indoor climate is greater than that of the visible works.
This article offers professional orientation as at the date of verification. It does not replace the assessment of a competent specialist.