Your Home Climate
Outcome

Breathe Better.

Recently reviewed·Reviewed June 2026, next review December 2026

Modern homes are airtight by design. Condensation, mould and stuffiness are the side effects; and the fix is quieter than most people think.

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Air Quality

Healthier homes you can breathe in.

Open the air quality chapter to see the technologies that contribute to breathe better.

How sure we are

Decision support, with the evidence shown.

Every recommendation below explains why it comes first, the evidence behind it, how confident we are, and when it would not apply.

Editorial confidence
High confidence. Multiple regulator, government or academic sources agree.
Evidence status
Recently reviewed · reviewed June 2026 · next review December 2026
Monitoring
Every winter, when condensation peaks.
Evidence drawn fromBuilding standards: ADF, CIBSEProfessional bodies: Loughborough DEFACTO, Passivhaus Trust, AECBIndustry evidence: BSRIA

You may not need to read the rest of this page

You probably already have enough to act if:

  • You know whether the problem is moisture, CO₂ or both.
  • You have monitor data, not just memory.
Open the comfort assessment

Indoor CO₂ for healthy cognition

< 1,000 ppm sustained

Source: Chartered Institution of Building Services Engineers · Above 1,500 ppm sustained, decision-making and concentration are measurably impaired.

Indoor relative humidity

40–60% year-round

Source: Building Regulations; Approved Document F · Below 30% irritates airways; above 70% supports mould growth on cold surfaces.

Whole-dwelling continuous ventilation rate

0.3 L/s per m² of floor area, minimum

Source: Building Regulations; Approved Document F · Approved Document F default; lower than this and pollutants accumulate.

Who this advice is for

Applies to

  • Homes built or substantially refurbished since 2010, where airtightness has outpaced ventilation.
  • Bathrooms and kitchens with extract fans that vent into voids rather than outside.
  • Bedrooms with condensation on the inside of windows on cold mornings.
  • Anyone with reported allergies, asthma or sensitivity to indoor pollutants.

Not intended for

  • Pre-1930 homes with chimneys and single glazing where natural infiltration is already high; the problem is usually heat loss, not air quality.
01

Put a CO₂ and humidity monitor in the worst-performing room for two weeks before buying anything.

Why this comes first

Indoor air quality is invisible; intuition is unreliable. A £40 monitor produces an evidence trail that decides between background ventilation upgrades, an extract fan, and full MVHR. Most homes spending on MVHR could solve the symptoms with continuous extract.

Evidence

Measure before you spend.

Loughborough DEFACTO · AECB

Confidence

High confidence. Multiple independent sources agree on the direction and the order.

Exceptions
  • Existing visible black mould; act first, measure during remediation.
Next step
Open the air quality assessment
02

Upgrade kitchen and bathroom extract to continuous low-rate before considering whole-house systems.

Why this comes first

Approved Document F now permits continuous low-rate extract as an alternative to intermittent boost. It removes moisture at the source, runs at ~15 dB(A) and uses less than 5 W. It solves 70% of condensation cases for under £400.

Evidence

Catch moisture at the source; don't try to dilute it later.

ADF · BSRIA

Confidence

High confidence.

Exceptions
  • Bathrooms with no external wall; ducting routes may rule out continuous extract.
Next step
Read: continuous extract vs MVHR
03

Reserve MVHR for properly airtight refurbishments where the heat recovery actually pays back.

Why this comes first

MVHR needs an airtightness of ≤ 3 m³/h.m² at 50 Pa to deliver advertised heat recovery; in a leaky retrofit the heat exchanger is bypassed by infiltration. Without an airtightness test, MVHR is a £6,000–£9,000 punt.

Evidence

MVHR is brilliant in an airtight envelope, mediocre in a leaky one.

Passivhaus Trust · AECB · BSRIA

Confidence

High confidence.

Exceptions
  • Post-2018 new builds with as-built airtightness < 3; MVHR is usually the right call from day one.
Next step
Open the ventilation hub

Evidence behind this page

Every recommendation on this page is traceable to its source. Click a publication to read the original.

How we'd approach this

Measure the air for a fortnight before specifying anything.

Most homes do not need a ventilation system; they need the ventilation system they already have to work. We would put a £25 CO₂ and humidity monitor in the worst-affected room for two weeks before anything is quoted. That single data set tells you whether the answer is trickle vents, a working extract fan, PIV or full MVHR.

If condensation is the visible symptom, we would treat moisture sources first. Lids on pans, vented tumble dryers and a humidistat-controlled bathroom fan resolve a surprising share of damp complaints without touching the fabric. They also tell you whether the underlying problem is ventilation, insulation or both.

MVHR is the right answer only where airtightness is realistic; below 3 m³/h·m² at 50 Pa the maths works, above it the kit is theatre. In leakier homes PIV is usually the more honest recommendation.

Real homes that pursued this

Publicly documented UK projects working towards breathe better.

We did not run these projects. Each links back to the original publisher so you can read the figures in context and judge what carries over to your home.

Your next step

The shortest route to breathe better.

Not theory; the tools and reading most likely to actually move this outcome in your home.