About ventilacion.cat: what this portal is

Who these pages are written for

Someone living in, buying or refurbishing a flat in Catalonia who did not grow up with how Spanish housing handles air. Not an installer, not a designer, not a surveyor.

More precisely, situations like these:

You have a symptom — glass streaming at seven in the morning, a dark corner that keeps returning, a bathroom that never dries — and no way to tell whether it belongs to the ventilation or to a different kind of damp.
You rent, and you want to separate what you can change yourself from what belongs to the landlord or to the community of owners.
You have just refurbished, and condensation has appeared that was not there before.
Your flat gives onto an interior light well, or has every window on one façade, and you want to know what that layout rules out.
A quotation has arrived in Spanish or Catalan and you are being asked to approve doble flujo, a recuperador and a caudal you have no way of checking.

A technician will find the official sources cited at the foot of each guide and can follow them. The text is not written for one.

What this site does not do

Worth stating in the negative, because that is the part that decides how far the rest can be trusted.

It does not install, design, commission, legalise or maintain any ventilation system: not controlled mechanical ventilation, not balanced systems with heat recovery, not shared vertical ducts, and not air conditioning.
It quotes for nothing, visits nothing, and assesses nothing at a distance.
It sells no equipment and names no brand or model as the right one.
It takes no enquiries and hands no contact to any company, for a commission or for free. There is no form and no phone number here, because there is nowhere for a name to be routed to.
It does not diagnose a particular dwelling. No page can decide, without standing in the room, whether a stain came from vapour generated inside or from water arriving from outside.
It gives no health advice. On damp and mould it goes no further than the World Health Organization's guidance supports.
It never asks you to do unsafe work: opening or altering a communal duct, electrical work, going up a façade, or applying biocides.

What changes when there is nothing to buy at the end

An international resident is unusually exposed to being sold the wrong fix. The material you can read fluently was written for another country's housing stock; the material about the flat you actually live in arrives in a language you are still learning, often attached to a price and a signature line.

A page with no funnel underneath it can stop where the evidence stops. It can say that a popular appliance does not touch the cause. It can say that the useful change is a gap under a door rather than a machine. It can say that the sensible move is to watch one season and buy nothing yet, or that the problem sits in a communal duct and no purchase you make alone will resolve it. Those conclusions sit badly on a page that has to end in a product, and they cost nothing here.

Five languages, each written from scratch

The portal is published in Catalan, Spanish, English, French and Russian. No version is a translation of another. Each is written from what that particular reader already takes for granted and what they do not.

The English pages assume you are measuring everything against housing somewhere else and have never met DB-HS3, the part of Spain's technical building code that deals with indoor air. They assume you will meet the local vocabulary before anyone explains it, so terms like caudal, simple flujo, doble flujo, recuperador de calor, shunt and patio de luces are given in both languages. The Catalan pages can go straight to the light well and the shared duct without defining either.

One warning belongs specifically in the English version. Whatever building rules you knew at home carry no weight in a Spanish flat: ventilation of dwellings here is governed by the Código Técnico de la Edificación, and fixed thermal installations additionally by the RITE. A figure, an expectation or an entitlement carried over from another country's regulations will not describe the property you are living in, however confidently it is quoted in an English-language forum.

Why the English section is smaller than the Catalan one

Of the ninety-eight guides on this site, twenty are in English. That is not an oversight or a temporary stage. It is the rule.

A page is written in a language when the research shows a distinct native-language question and enough local scope to answer it properly. That is not a claim of equal measured search volume: usable volume data was available for Spanish, while the other launches rely on native-language intent and SERP review. Translation parity would manufacture text without proving that editorial need. Catalan and Spanish are the deepest versions, English covers a broad part of the ground, and French and Russian concentrate on the core — how ventilation in a Spanish flat is supposed to work, condensation, and bathrooms.

The language control at the top of a page offers only the languages that exact page genuinely exists in. If yours is not listed, that text has not been written yet; it has not been hidden from you.

There are no category pages in English either. Splitting twenty guides across a full set of categories would produce thin category pages of no use to anyone, so the English guides sit directly under /en/ and are reached from the English home page, which is sorted by symptom rather than by system.

Visible mould and the air in the room are two different jobs

When mould appears on a wall, two problems are stacked on top of each other, and separating them saves money. One is the affected material itself, which has to be assessed, treated and removed with professional judgement. The other is why that surface stays wet enough for something to grow on it.

This site deals only with the second, and only by explaining it. Where visible mould is already the immediate problem, some guides link contextually to NoMoho, the commercial mould-remediation project in the same portfolio. Read that link as a boundary, not a joint ventilation offer. NoMoho does not offer ventilation or air-conditioning work on behalf of this portal, and this site does no work in anyone's home at all.

The caveat belongs here rather than in small print. Ventilating better does not guarantee that mould will not return: it also depends on how much moisture the household produces and how cold the coldest surfaces stay. And not every damp problem is condensation to begin with — a leak, rising damp and rain penetration are different mechanisms with different remedies, and telling them apart takes someone on site.

What you can check before trusting any of this

The publisher is Aleksandr Prokofyev, a self-employed worker in Spain; the legal notice carries the complete identifying details. That editorial identity is not presented as an engineering qualification, trade registration or installer certification, because none has been verified. Nor is a named technical expert presented as reviewer. What can be checked is this:

Technical and regulatory statements carry their official source at the foot of the guide — the CTE's DB-HS3, the RITE, the World Health Organization guidance on dampness and mould, among others. Where there is no source, the claim is not made.
Every guide shows the date it was last revised, so you know which version of the text you are reading.
Every guide carries a section on what it does not solve. Those limits are part of the content, not a legal disclaimer.
The editorial methodology page sets out how subjects are chosen, how pages are checked and what is deliberately left out.
If you find a factual error, the contact page explains the route for pointing it out.

One rule runs through all of it. Once a decision involves building work, calculations, communal installations or serious money, what you need is an on-site assessment by a competent professional. These pages are written so that you arrive at that conversation knowing what to ask and what to look at.