Louis Airy

A high-performing envelope is often decided by details. For you, the tradesperson, the real difference happens at the junctions, around window frames, at the base of walls or in the roof, where breaks let heat escape and complicate airtightness. By securing continuity all the way around, you gain comfort, compliance, and calmer client follow-ups.

5 min read

With lukewarm-water emitters, every watt counts. On site, oversizing can secure comfort during cold snaps, but it also means more bulk, more inertia, and sometimes a network that needs adjusting. By mastering power calculations, flow temperature, and balancing, you size things right and avoid callbacks.

5 min read

Your client has a fireplace that heats poorly and burns through fuel. By modernizing it with a pellet appliance, you gain in comfort, consistency, and cleanliness, without starting from scratch. With a well-prepared installation, you secure the flue, simplify daily use, and add value to the job in your clients' eyes.

5 min read

No regulation sets a service life for a water heater, and the durations in circulation carry no legal weight anywhere. What can be decided and quantified is the point at which keeping the unit costs more than replacing it. Three criteria settle it: the declared standing loss, the row the energy assessment already applies to the unit, and the compliance of the installation.

6 min read

The choice between a vertical and a horizontal electric cylinder is settled by the room, not by the data sheet. Horizontal only becomes necessary when clear height runs out, and it then costs 419 kWh a year more at 200 litres according to the French EPC calculation method. Here is what to record before pricing, what makes an installation overrun, and how to justify the running-cost penalty on the estimate.

6 min read

In renovation, you can improve comfort without piling on equipment, by starting with orientation, sun, wind and the building's thermal mass. These simple markers help you decide quickly, justify your choices to the client and avoid contradictory work. When the building "works" for you, your technical solutions become leaner and easier to deliver on site.

5 min read

A client complaining about a whooshing sound or vibrations in the ventilation system is often a job that can tip into dissatisfaction. As a tradesperson, you can quickly diagnose the cause — clogged vent, poorly fixed duct, wrong flow rate — and restore comfort without redoing everything. With a few simple actions and the right choice of equipment, you cut the noise and keep air quality on track.

5 min read

On a job, an error in surface area or a "default" output figure can quickly wreck profitability and client satisfaction. You need simple benchmarks to size correctly, without over-equipping or underestimating, from the very first estimate. We sort out the practical field values from the assumptions that send a quote off track.

5 min read

In a retrofit, the hot water going down the drain can still earn you kWh, especially from showers and small multi-unit buildings. As a tradesperson, this is a simple option to build in when a client wants to cut their bill without major work, provided you spot the right uses and installation points. Here, we lay out the principle and the cases where it's genuinely worth it.

5 min read

On site, you spot it quickly, a dwelling that ventilates poorly means condensation coming back, odours settling in, and clients calling you back. With a few simple steps, you secure air quality and stop dust and grease from bringing down the airflow. Regular checks mean more comfort, fewer callbacks, and a service that's easy to sell.

5 min read

A thermodynamic heat-recovery unit is sold as ventilation that heats. The question nobody asks at quote stage is how much heat the supply air can actually carry, and that is bounded by the regulatory flow rates. We work it out here, along with what the French EPC keeps from the machine and what the decree of 17 November 2020 requires for the grant.

5 min read

Sizing a solar array for self-consumption comes down to one division: annual daytime consumption divided by the local yield in kWh per kWp. Everything else is the quality of those two terms. The yield comes from PVGIS, not from a national average, because it varies by a quarter between Glasgow and Plymouth. Daytime consumption comes from the half-hourly meter data, not from the annual bill.

6 min read

A tapping profile is a standardised draw-off sequence, not a marketing estimate. Regulation (EU) No 814/2013 defines ten of them, from 3XS to 4XL, each with its reference energy Qref and its maximum flow rate. The declared profile sets the water heating efficiency the appliance has to meet, and therefore what you can commit to on a quotation.

5 min read

Between selling all your production and using it on site, the right choice often comes down to 3 simple points: your client's profile, their usage patterns, and the actual value of a kWh depending on the time of day. As a tradesperson, you save time by asking the right questions upfront, then costing two clear scenarios, with no vague promises.

4 min read

External wall insulation under wood cladding turns on two sets of values, not on the choice of timber species. The first comes from NF DTU 41.2 and fixes the air gap, the ventilation and the framing: it decides whether the façade lasts ten years or comes back as a claim. The second comes from the grant schemes and fixes the thermal resistance of the insulation, with a threshold that changes depending on whether the work is a single measure or a whole-house retrofit.

5 min read

In a water heater, the anode does the quiet job that keeps you from getting a callback for a perforated tank. Magnesium, titanium or impressed current, each solution has its own installation habits, checks and pitfalls, and that's often where everything is decided. Get this choice right and you secure the installation's lifespan and your client's peace of mind.

5 min read

When you add a recirculation loop to the domestic hot water (DHW) system, your clients gain comfort, and you gain peace of mind on callbacks. But that continuous circulation can also push up losses in the pipework, especially if insulation and control are rough. Getting the setting right is often just a few hours of fine-tuning to stop kWh leaking into the walls.

5 min read

When you play with orientation, opening size and the right solar shading, you gain comfort right away. Fewer dark zones during the day, less overheating in summer, and clients who feel the difference without needing a lecture. It's up to you to turn daylight into a real renovation lever, simple to explain and easy to price.

5 min read

When a customer hesitates between a heat-pump water heater and a solar water heater, it's often your ability to compare quickly and clearly that makes the difference. Real-world efficiency by climate, available space, noise level, maintenance, subsidies: you already have the right criteria, provided you ask them in the right order. Here we get straight to the point to help you decide job by job, no fluff.

5 min read

When a roof has shade, a nearby chimney or mixed orientations, output can drop faster than expected. Module-by-module control protects yield on the penalized zones without redoing the whole array. It's also a good lever for diagnosing issues, explaining them to the client, and delivering a more consistent PV installation, job after job.

6 min read

The reference figure for domestic hot water consumption is not a sales estimate. The French 3CL-DPE 2021 method uses 56 litres per person per day at 40°C for conventional behaviour and 79 litres for heavy use. The instrumented ADEME and COSTIC monitoring campaign lands on the same measured average, with a standard deviation of 23 litres.

5 min read

A well-insulated garage closure is often the difference between a workshop that stays comfortable and a job site where the cold creeps in everywhere. For you, as a tradesperson, the right choice comes down to concrete points, insulation thickness, airtightness, installation quality and compatibility with the motor. By framing these criteria from the start, you avoid callbacks and secure the expected thermal performance.

5 min read

When an MVHR system is properly sized, you notice it right away, less lingering humidity, odours that don't come back, and clients who breathe easier. But it all comes down to job-site details, air inlets, extract vents, and room-by-room airflow balance. Get these right at installation and you avoid callbacks while securing the home's performance, without the headache.

5 min read

On an insulation job, you're juggling dust, cuts, falls and irritant products. With the right PPE and simple habits, you protect your team without slowing the pace, and you keep a clean, professional site. Mask, goggles, gloves, ventilation, clearly defined work zones — this is often where the difference is made.

5 min read

This article covers the heat pump and underfloor heating pairing from the site side: pressure testing, screed movement joints, first heat-up, residual moisture and the handover file. Sizing the pairing, heat loss, water regime and minimum modulated output, is the subject of a separate article.

5 min read

On some jobs, adding a buffer tank can make your life easier — or, on the contrary, complicate an installation that was already running smoothly. Between short cycling, the minimum flow rate to respect, and highly reactive emitters, the right choice comes down to a few site-specific details. By quickly spotting the cases where it genuinely stabilises operation, you secure the client's comfort and your commissioning settings.

5 min read

Efficiency is the most quoted and least verified figure on a ventilation quote. Three frameworks measure it, with three different values, and only one binds you when you assemble a grant file. Here is how to read a datasheet, which threshold commits you, and what the unit really delivers once the ductwork is in.

5 min read

When you're looking for where heat is escaping, you need a simple benchmark that sums up envelope losses without drowning you in ten different values. A good overall indicator helps you prioritize quickly, insulation, joinery, thermal bridges, and clearly explain your choices to the client. The payoff: clearer quotes and better-targeted work from the very first visit.

5 min read

The choice between self-regulating and humidity-controlled ventilation does not come down to a fitting preference but to a single figure: the floor flow rate you are allowed to hold. The French order of 24 March 1982 sets two different floors depending on whether the system modulates automatically, and the gap between them is close to a factor of three. Everything else, comfort, acoustics, consumption, follows from that.

5 min read

You're hearing more and more about decarbonized gases on job sites and from your clients, but between promises, costs, and constraints, it's hard to know what will actually hold up over 10 to 20 years. Your challenge is spotting the credible use cases, the equipment that might arrive, and the points of attention on safety, network, and maintenance, so you can advise without overselling. Here's a simple sort-through, to help you decide when to keep an eye on the topic, and when to stick with solutions that are already robust.

5 min read