A house project, whether it involves construction or heavy renovation, relies on a sequence of technical and financial decisions where the order is as important as the content. Mismanaging this sequence exposes one to additional costs or the need to redo work. This article details the methodological points that separate a well-managed project from a poorly executed one.
Energy remaining: the banking criterion that changes the game
Since 2024, several French banks have integrated an energy remaining into their financing studies. The principle: borrowing capacity is weighted according to estimated future energy bills after work is completed, in accordance with the requirements of the revised European directive on the energy efficiency of buildings (EPBD revised, published in the Official Journal of the EU on May 8, 2024).
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In practice, a project that incorporates effective insulation or an energy-efficient heating system obtains a better borrowing capacity than a simple refresh. The renovation budget and the financing budget are no longer two separate subjects: decisions on insulation materials or the ventilation system directly influence the amount the bank is willing to lend.
Even before consulting a builder or architect, it is useful to gather available information on the dedicated page of Ma Maison Info to outline the main aspects of the project and its financial implications.
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Scenario-based energy audit: structuring work in stages
For renovation projects aiming for a leap of several energy performance classes, engineering firms and architects now systematically present two or three work scenarios rather than a single package. This practice, documented by France Rénov’ since the reform of mandatory energy audits for F and G housing in 2023, allows for phasing interventions over several years without compromising final performance.
Each scenario corresponds to a distinct level of ambition:
- A “minimum regulatory” scenario that focuses on the most energy-consuming areas (attic insulation, replacement of the heating system) to meet the legal threshold.
- A “optimal performance” scenario that aims for an A or B class by combining external insulation, double-flow ventilation, and solar hot water production.
- A “cost-neutral over fifteen years” scenario that balances the cost of work with projected energy savings, so that the initial additional cost is offset by lower bills.
Having these scenarios before signing a quote allows for informed negotiation of each lot. Phasing also avoids mobilizing the entire budget in the first year, freeing up a margin for unforeseen construction issues.
Linking the audit to financing
The scenario chosen in the audit directly feeds into the bank file. The more documented the projected energy gain, the more the energy remaining works in favor of the borrower. Providing the complete audit to the bank at the time of the loan application shortens processing times.
Choice of materials and quality of work: two linked areas
An effective material poorly installed loses a significant part of its properties. A common mistake is to compare only the prices per square meter without checking the compatibility between the chosen material and the expertise of the selected company.
For new construction, the choice of construction method (cinder block, monomur brick, wood frame, cellular concrete) conditions the entire chain: foundations, type of insulation, treatment of thermal bridges, and timelines for waterproofing. Changing the construction method mid-project leads to costly rework on already committed lots.
Check technical coherence before signing
Before accepting a quote, three points deserve special attention:
- The exact reference of materials (and not just the product family) must be included in the quote. An “insulating glass wool” without thickness or thermal resistance indicated allows for no control upon receipt.
- The management of interfaces between lots (who ensures airtightness between the framing lot and the insulation lot, for example) must be specified in writing.
- The provisional schedule must mention drying times or non-compressible setting times, under penalty of having a screed poured on a still damp substrate.
These technical details are not always included in standard contracts. Requesting them in writing before the start of the work provides the best protection against defects.
Site monitoring: what the project owner must actually control
The project owner (the individual having construction or renovation done) does not need advanced technical skills to ensure effective monitoring. Their role is to verify the conformity of what is done against what is written.
At each key stage (foundations, waterproofing, air-tightness, finishing work), photographing the state of the site and comparing it to the description in the quote is sufficient to identify most discrepancies. In case of doubt, a spot check by an independent project manager costs much less than redoing work after acceptance.
The reservations at acceptance
The acceptance of the work is the legal act that triggers the guarantees (perfect completion, biennial, ten-year). Any visible anomaly not recorded in the acceptance report will be more difficult to correct later. Listing each defect, even minor, protects the project owner throughout the duration of the legal guarantees.
A well-managed house project does not rely on an accumulation of generic advice. It is based on a rigorous sequencing: first the audit and financing, then the choice of materials in line with the construction method, and finally documented monitoring up to acceptance. The quality of a project lies in the order of decisions, not in their number.