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A building envelope is a critical part of any building, whether it’s private or commercial, your home or your office. But if you’re new to the construction industry or certainly new to the language used in the construction world, you might be unaware of what this term means.

That is why we have created this guide. Below, we are going to take a look at what a building envelope is, why it matters and the different types. This will help to explain this important stage of the construction process and build on your knowledge for the future.

Read on to find out more.

What is a building envelope?

As we’ve said, a building envelope is a very important and critical part of any building. In layman’s terms, it is the exterior or shell of a building; it essentially encloses the structure. The main purpose of the building envelope is to keep out the elements and facilitate climate control inside.

However, it does play other important functions, including protecting the interior and keeping it safe from outside forces and hazards, providing an aesthetic appeal and, in some cases, offering mechanical or structural load support.

Essentially, a building envelope is a physical barrier between the conditioned and unconditioned environment. Therefore it must be resistant to air, water, heat, light and noise transfer.

It’s worth noting that a building envelope is not one large item placed over a property; rather, it is a collection of smaller elements that all work together to provide protection, structure and support. This is why it must be so carefully thought out and put together for the best possible results.

Why do building envelopes matter?

We’ve briefly touched on this in our definition, but there are several reasons why a strong building envelope matters. As one of the key functions is climate control, a strong and stable building envelop is vital for:

• Moisture control – Moisture can take its toll on a building and cause damage over time. Therefore, the envelope must be able to regulate the transfer of moisture inside and out
• Air control – Similarly, controlling airflow is the key to controlling energy consumption. A good building envelope must allow for the right amount of airflow to provide a quality and comfortable climate indoors and to avoid condensation building up and doing damage
• Thermal control – Finally, it is responsible for helping to regulate the temperature and overall climate indoors, ensuring it’s not too hot or too cold. Again, this can be closely linked to energy consumption

And these are just a few ways in which the building envelope is important for the overall structure. It plays such a critical role in regulating temperature, dealing with moisture and protecting the longevity of a building.

What are the different types of building envelopes?

There are two broad types of building envelopes, and we’re going to take a look at these in more detail below. The two categories are tight, and loose building envelopes and which you choose will depend on the type of structure and what you want the envelope’s main purpose to be.

In the simplest form, a loose building envelope allows for more natural airflow to occur within the structure. On the other hand, a tight envelope plays the opposite role; it is designed to be as airtight as possible in order to stop air leaks. Let’s now dig a little deeper.

Loose envelope designs

Loose envelopes are often used to eliminate the need for an indoor mechanical ventilation system because the structure allows for more direct airflow. This can improve the overall indoor air quality. These might be used for larger buildings that hold more people and therefore require more natural ventilation.

However, loose envelopes tend to be much draftier and give you less control over the indoor climate. It can also increase energy usage and moisture build-up, which can lead to an increased risk of mould and mildew.

Tight envelope designs

Finally, tight building envelopes, as the name suggests, are very tightly constructed to ensure there are very few air gaps, drafts or breaks in the structure. This system regulates the air transfer in and out, typically using vents and other mechanical forms of ventilation and air conditioning to do this.

This type of envelope can help you to save on your energy usage and costs, as well as giving you more control over the interior climate. This also reduces the risk of moisture and issues like mould and mildew building up inside. It makes it much easier to maintain the building and can protect it from damage for far longer.