How Your Insulation Choices Affect Indoor Air Quality

You crack the window open when you’re cooking. You run the extractor fan in the bathroom. You might even have a favourite “fresh linen” spray for soft furnishings.

But here’s something most of us never think about: the insulation inside your walls can also have an impact on the air in your home.

Let’s talk about VOCs….what they are, why they’re worth knowing about, and how choosing the right insulation can support a healthier indoor environment.

What Exactly Are VOCs?

VOCs stand for volatile organic compounds. They’re carbon-based chemicals that easily evaporate at room temperature, turning from solids or liquids into gases. That “new car smell”? VOCs. The sharp scent when you open a tin of paint? Also VOCs.

They’re almost impossible to avoid completely. VOCs are emitted from thousands of everyday products: cleaning supplies, air fresheners, cosmetics, dry-cleaned clothing, and building materials like insulation, adhesives and composite wood products.

The tricky part? You often can’t see or smell them at lower concentrations. But they’re still there. And because we spend roughly 90% of our time indoors, where VOC concentrations can be higher than outdoors, our overall exposure tends to come mainly from inside our homes and workplaces.

Why Should You Care?

For most people, everyday, low-level exposure to VOCs doesn’t cause noticeable problems. But higher levels - or a combination of lots of different sources - can start to have effects.

Short-term exposure to elevated VOC levels can be linked with:

• Eye, nose and throat irritation
• Headaches and dizziness
• Nausea
• Worsening of asthma symptoms

These kinds of symptoms are easy to dismiss as tiredness or “just one of those days”. For people with respiratory conditions like asthma, VOC exposure can sometimes worsen symptoms or contribute to flare-ups.

Long-term exposure to certain VOCs at higher levels has been associated in studies with more serious health effects, and some VOCs – including formaldehyde and benzene – are known or suspected carcinogens.

Children, older adults, and anyone with existing health conditions can be more sensitive to poor indoor air quality. At the same time, modern, well-sealed homes that are excellent at keeping heat in can also hold on to indoor pollutants for longer if ventilation isn’t carefully considered.

We don’t want you to panic. It’s about awareness. You can’t remove VOCs completely, but you can make informed choices that help keep levels sensible – especially in the rooms where you sleep, work and spend most of your time

The Insulation Problem

Insulation plays a big role in how comfortable, energy efficient and quiet a building feels. But some conventional insulation materials - particularly fibreglass, foam boards and spray foams - can be a source of VOCs through a process known as off‑gassing.

This off‑gassing happens when chemical binders, resins or petrochemical components slowly release gases over time. Some products off‑gas more around the time of installation and then settle down; others can release low levels over longer periods.

For example, spray foam insulation, popular for its airtight seal, has been scrutinised for the compounds it can release during and after installation, which is why installers often recommend that properties aren’t occupied during application. Fibreglass batts, the itchy stuff many of us have seen in lofts, typically contain binders that have historically included formaldehyde, although newer products have reduced these emissions.

The point isn’t that these materials should never be used. It’s that, as awareness of indoor air quality grows, more people are starting to ask what’s in the products that sit behind their walls and ceilings.

What Makes Sisalwool Different?

Sisalwool™ is a natural fibre insulation made from wool and sisal fibres – two renewable, plant and animal-based materials that have been used in construction and textiles for generations.

Sisal has a long history in building and agriculture in the form of ropes, twines and composite products, while wool has been used for centuries in insulation, roofing and wall applications across Europe.

The key differences?

• Comfortable to work with: No itching, no obvious dust clouds, and no need for full protective suits for most straightforward installations.
• Breathable by design: Natural fibres help manage moisture, supporting constructions that are less prone to condensation and mould – both of which can affect indoor air quality.
• Renewable and low‑carbon: Both wool and sisal are rapidly renewable, biodegradable materials with a lower embodied energy than many synthetic options.
• Built for the long term: Sisalwool is resistant to mould, pests and degradation, meaning it continues to perform for decades when correctly installed.

We’re confident enough in our materials to put it plainly: everything that goes into Sisalwool is chosen with indoor air quality and occupant wellbeing in mind. That includes our moth and fire treatments, which are formulated to do their job effectively without relying on harmful chemicals…..so you’re not solving one problem only to introduce another.

The Bottom Line

You can’t control everything in the air outside. Inside your home or building, though, you have a bit more say.

Choosing insulation that supports good indoor air quality is one of those quiet, behind‑the‑scenes decisions that can make everyday life more comfortable over the long term. It’s not something visitors will ever see – but you’ll feel the benefit in how your building performs and how it feels to live or work there.

Because at the end of the day, a well‑insulated building should feel like a comfortable, safe place to be – not something you have to worry about.

Want to learn more about natural fibre insulation? 

Explore Sisalwool's full range and technical specs at sisalwool.com.