Pierre-Louis Guhur

Radon kills 2,500 to 3,000 people a year in France. Dosimeter measurement, slab airtightness, redesigned ventilation and SSD: the technical levers to master during renovation.

6 min read

When the outdoor temperature drops, that's often when your clients judge comfort… and when the settings make all the difference. By mastering the logic behind varying the heating-water temperature with the climate, you save time on call-outs, cut down on 'it's not heating' calls, and secure consistent consumption. A few simple reference points are enough to get it right from commissioning.

5 min read

When several trades share a whole-house renovation project, the real headaches rarely come from the materials. They arise at the junctions — one trade arriving too early, another changing a detail, and the whole schedule slips. With a simple method for sequencing tasks, checkpoints and proof of completion per trade, you secure quality, deadlines and your margin, without drowning in paperwork.

5 min read

On a job site, it's not your margin that gets you into trouble, it's the gap between your outgoings and your incoming payments. Between the deposit, progress payments, and retention money, a few weeks of slippage is enough to freeze your purchasing and your schedule. With two or three simple habits, you stay in control of the timelines and secure your jobs without wearing yourself out.

5 min read

On site, the real question isn't the 'best COP' on a spec sheet, but what the machine delivers when demand drops, in mid-season or when just holding temperature. At partial load, a heat pump can gain in efficiency… or collapse if the controls and sizing don't keep up. By mastering these gaps, you protect the quoted consumption figures and your clients' satisfaction.

5 min read

In rural areas, when the gas network isn't there, you need to offer a reliable solution that's simple to maintain and acceptable both on the quote and in use. Tank propane often ticks these boxes, with comfortable output and an installation that adapts well to older homes. Here, the challenge is to secure the sizing, the tank's placement and the right settings to avoid overconsumption and callbacks.

6 min read

The expansion valve meters the feed to the evaporator and sets the superheat. Replacing or adjusting one means opening the refrigerant circuit, and it is that opening, not the part, that triggers the duties: leak checking based on the charge in tonnes of CO2 equivalent, an intervention record, five years of retention. Here are the adjustment references, the valve types and the interval table.

5 min read

Between a heat pump and a gas boiler, the difference isn't only in the quote: it's also in the environmental impact over the equipment's entire life cycle. This article works through the DESNZ conversion factors, the SCOP assumptions to use in retrofits, the role of the refrigerant (R32 vs R290), and gives sourced orders of magnitude for your on-site recommendations.

5 min read

An underfloor cooling system is not air conditioning, and the CSTB technical guide that governs it in France assigns it no cooling output at all. It even accepts that indoor temperature will rise once the load exceeds what the floor can absorb. What it does impose is written down: a minimum flow water temperature by geographic zone, a safety cut-out at 12°C, and limits on the covering's thermal resistance. Here are the figures, and what belongs on the quotation.

5 min read

The French indoor-air value for formaldehyde changed on 1 January 2023, and not in the direction everyone expected: the 30 µg/m³ long-term figure disappeared, replaced by 100 µg/m³ over a short exposure. Plenty of trade literature still quotes the old value, or a 10 µg/m³ deadline that never came into force. Here is the current text, and the labelling thresholds you actually select products against.

6 min read

At rafter level, U = 0.16 W/m².K asks for around 210 mm of mineral wool at λ 0.035, close to 230 mm off the slope once the lining is on. Approved Document L says so itself in Table 4.3: where that would limit headroom, a lesser standard may be appropriate.

6 min read

When a client wants to move off gas, it's often up to you to quickly decide between an individual solution and a collective option, without promising the impossible. Between power constraints, available space, noise, connection work and support schemes, the right choice is decided on site, not on a product sheet. With a simple site-visit and costing method, you secure the decision and avoid callbacks.

5 min read

With a multi-split system, the right number of indoor units is the one that matches the living spaces and usage patterns, not a one-size-fits-all rule. As a tradesperson, the challenge is simple: cover the right volumes without oversizing, while keeping the installation tidy, accessible and easy to balance. Starting from the floor plan, the gains and the installation constraints, you produce a clear quote and avoid callbacks.

5 min read

On a renovation job, correct sizing is what separates a smooth-running project from a string of callbacks. When the machine is too powerful or too marginal, you pay for it with short cycling, discomfort and climbing consumption. By mastering 5 common pitfalls, you secure your quotes and save time from the study phase onward.

5 min read

In an unheated loft, a poorly insulated ventilation duct can quickly cause condensation and airflow loss, followed by service calls you could have avoided. With a few good habits around choosing the insulation, sealing the connections, and routing the ductwork, you secure the job's performance and durability. The idea is to keep air circulating well, with no moisture creeping in where it shouldn't.

5 min read

R744 is not a fluorinated greenhouse gas. It sits outside EU Regulation 2024/573, and therefore outside the quotas, the Article 5 leak checks and the Annex IV bans. What constrains it lies elsewhere: the high pressure of the transcritical cycle, the hot water temperatures set by the French order of 23 June 1978 as amended, and, since the French order of 21 November 2025, a category B company certificate, carbon dioxide having entered the scope of certification.

5 min read

This article deals with the air-to-water heat pump and underfloor heating pairing from the sizing side only: the output the floor can actually deliver under the applicable caps, the water regime that follows, and the minimum modulated output the machine has to be able to hold. The site work, testing and heat-up, is covered in a separate article.

5 min read

When a client is torn between dry and fluid thermal mass, you're often the one who settles it. It's up to you to turn two closely related technologies into a simple choice, discussing comfort, responsiveness, maintenance and installation constraints. With a few clear benchmarks, you secure the quote and avoid callbacks.

5 min read

In 2026, the choice of refrigerant is no longer a minor detail. On site, it can tip a sale between compliance, performance and equipment availability. Between tightening bans and new refrigerants with a lower climate impact, you need a simple benchmark to propose the right solution, without risk to your client or your schedule.

5 min read

When your schedule is already full, the real lever is not adding more hands. It is making every job more valuable, by pricing more accurately, framing better, and cutting the "invisible" hours that eat into your margin. You can grow your revenue without hiring, by making your quotes more profitable and your teams more efficient, starting in the next few weeks.

5 min read

Summer comfort has only one official set of figures in France, and it applies to new build alone: the RE2020 discomfort degree-hours. In a retrofit no text sets a threshold, which means your written commitment on the quote is the only document anyone can hold you to. Worth knowing exactly what RE2020 measures before promising anything.

5 min read

On a job, knowing exactly when to stop heating isn't about comfort, it's about control and lower bills. With a simple calculation method, you can justify this threshold to the customer and set your controls according to insulation, building thermal inertia and free gains (sun, usage). The result: less overheating, cleaner regulation, and works whose impact shows up in consumption figures.

5 min read

On an energy retrofit job site, everything often comes down to the order of operations. As a tradesperson, you save time, secure performance and cut down on rework when you start with the right measures at the right moment. From the building envelope to the systems, here's a simple method to help you decide fast, without guesswork or overpromising.

5 min read

When a client wants comfort in both summer and winter, you have to decide quickly between output, efficiency and placement, without turning the job into a headache. With a good reading of room-by-room needs and a few points of vigilance on noise, units and controls, you can offer a solution that both heats and cools, while staying simple to maintain.

5 min read

On an external wall insulation job there is not one thermal resistance threshold but three, and they do not measure the same thing or come from the same texts: 3.2 m².K/W on the complete wall under the trigger-work obligation, 3.7 on the insulation alone for the BAR-EN-102 certificate sheet, and 4.4 for external insulation in the MaPrimeRénov' guided route. Mixing them up means pricing a thickness that will not pass inspection.

5 min read

When your clients want to renovate without getting lost in grants, quotes and technical choices, you're the one who brings order to it all. With a simple 5-point method, you save time, secure the job, and explain the value of your recommendations more clearly. Enough to move quickly, with no vague promises or unnecessary complexity.

5 min read

On a roof, orientation and the zone you're working in change everything, both for summer comfort and for winter gains. By mastering the coverage factor, you can justify your choices to the client without endless calculations, and secure the actual performance of the job. The idea is simple — aim for the right balance between protection and gains, based on the façade and the local climate.

6 min read

Between a single system and room-by-room equipment, the question isn't the technology, it's the right project scenario. As a tradesperson, you save time when you know where the real costs hide — network to build, maintenance, controls, and above all how the home is actually used. The idea is to choose the solution that holds up over time, not just on the quote.

5 min read

On a job site, mistakes don't forgive. A gap in a quote, poorly checked information about a grant, and you lose time, or even end up with an unhappy client. With an AI assistant built for energy-renovation professionals, you secure your answers, your technical choices and your deliverables, without drowning in paperwork.

4 min read

For sizing that holds up, everything hinges on the right local cold-weather scenario. As a tradesperson, this benchmark is what keeps you from installing a heat pump that runs at overcapacity or, conversely, an oversized system that costs more and regulates poorly. With a few simple checks, you can secure your power choice and your on-site performance.

5 min read