Choose carefully when certifying your building project

All the leading certification schemes for sustainable building take account of the indoor climate. Even so, there are crucial differences in how the schemes weight the various criteria.

A building’s size and type also matter. This makes it important to consider the specific aspects of the indoor climate you wish to document when choosing a scheme.

Today, developers and consultants can choose from a number of recognised certification schemes, each documenting the sustainable properties of buildings in a number of areas. In this context, indoor climate is an important part of the equation.

But the way in which each scheme specifically deals with the indoor climate is vastly different. For instance, WELL, a US certification scheme, focuses primarily on social sustainability and emphasises health-promoting criteria such as air, light and sound, but generally fails to consider environmental or financial sustainability. The older schemes BREEAM and LEED give high priority to the environment, but consider the financial aspects to only a limited extent.

Several schemes have regional variants that take account of local climate, building traditions and legislation. Moreover, the type of building is also important, as some criteria are included in the certification of office spaces and public buildings, but not in the certification of dwellings.

Researchers: Vast differences in the certification schemes

“The differences between the certification schemes can make it difficult to choose the right tool to assess the indoor climate,” point out Tine Steen Larsen and Lasse Rohde, both of whom are researchers at BUILD – Department of Construction, City and Environment, Aalborg University, Denmark. They have authored a report that examines and compares how the five internationally recognised certification schemes – BREEAM, LEED, DGNB, WELL and LBC – each of which weight the indoor climate for the certification of dwellings.

“The way the certification schemes look today, it’s difficult for both the construction industry and end-users to decipher what the individual certifications actually say about a building’s indoor climate and how it affects the users, the environment and society. This prompted us to create an overview of how the schemes weight different parameters in terms of the indoor climate,” Lasse Rohde says.

How should air, light and acoustics be weighted?

The researchers’ comparison examines the indoor climate issue in a holistic perspective, focusing on four main categories, each with a number of subcategories:

Thermal indoor climate (including utility temperature, cooling and draughts)
Acoustics (including reverberation time and sound insulation)
Visual indoor climate (including daylight, electric light and field of view)
Indoor air quality (including ventilation capacity, air filtration and degassing from materials)

The comparison also assesses users’ possibility of controlling the indoor climate by means of ventilation and temperature adjustment, for example.

Out of all the criteria examined, only indoor air quality and user controls are included in all the schemes. In LEED and LBC in particular, air quality is weighted particularly heavily, while the various criteria are more evenly dispersed in BREEAM, DGNB and WELL. LEED for Homes stands out from the other building certification schemes under LEED, however, as it only considers air quality. The LEED certification of other types of buildings encompasses other aspects, but as the study was aimed at dwellings, these are not apparent in the comparison.

“Generally speaking, all the certification schemes for dwellings – BREEAM, DGNB and WELL – adequately cover the four main criteria, whereas LEED and LBC do not provide a complete picture of the indoor climate. The specific subcategories included in the individual certification schemes vary somewhat. DGNB provides the broadest coverage in terms of unifying financial, environmental and social sustainability, whereas it’s beneficial to use WELL together with other certification schemes,” Tine Steen Larsen says.

The figures below show researchers’ comparison of how indoor climate is weighted in the various building certification schemes.

As the figure shows, the various certification schemes vary greatly in terms of how they quantify the indoor climate.

All schemes used in the comparison are aimed at dwellings.