Green certification of existing buildings is rare but will probably increase over time. Jochen Schenk reveals the details of two case studies

The green certification of new buildings is nothing new, but few existing properties have been certified so far. The challenges differ and the procedures for the latter have barely been tested on the ground.

The buildings ‘The Book’ in Amsterdam and ‘K-LAN’ in Düsseldorf are rare examples of existing office stock certified as green buildings under Building Research Establishment Environmental Assessment Method (BREEAM) and German Society for Sustainable Construction (DGNB), respectively.

The certification of existing buildings involves close scrutiny of tenant consumption figures, which is not limited to heating and water. Waste separation, protecting non-smokers and detergent use are also taken into account, as is the property’s technical fit-out.

Certification for K-LAN was commissioned by Real IS and facilitated by the company’s engineers. The first problem was which green building standard to choose and which rating to aim for. The objective was to demonstrate that an existing building in Germany, raised under the strict DIN standard or in accordance with the Thermal Insulation Ordinance (WSchV), would qualify for a green building certificate without major retrofitting measures.

Built in 2002 with nearly 25,000sqm of gross external area, the office scheme in Düsseldorf had been vacated by the original tenant prior to the certification under the DGNB standard and had not been reoccupied. Accordingly, the assessment used the consumption figures of the former tenant to determine the key ratios considered for the green label. The energy efficiency was evaluated on the basis of three years’ energy consumption. In terms of environmental quality, the property achieved a 1.97 rating.

The score was better yet when it came to the evaluation of the economic quality. This assessment focused on the property’s alternative use potential and involved aspects like space efficiency and potential conversion options. The building scored 87% under this criterion and an overall grade of 1.93 for economic quality.

Real IS then decided to capitalise on the property’s alternative use potential. The company converted what used to be a single-tenant building into a scheme that provides flexible office solutions such as co-working areas for a variety of companies. It features coffee points and all-day lounges and thus encourages social interaction. Socio-cultural and functional qualities were also assessed in conjunction with the re-certification. The quality of the grounds and disabled access were rated ‘good’.

In the technical quality category, the building rated 1.93, not least because of the absence of harmful substances. The great results reduced the technical upgrading requirements to a minimum. Ultimately, the property scored an overall DGNB rating of 2.58 and was awarded exactly the DGNB In-Use certificate in bronze.

In February 2013, a green in-use certificate under the BREEAM NL BBG standard was awarded to The Book. The building scored ‘excellent’ in all three categories of asset performance, building management performance and organisational effectiveness. This makes it one of only five properties in the Netherlands that scored in all three categories. Indeed, The Book achieved the second-highest result of all.

The certification pursuant to the BREEAM standard adopted in the Netherlands was masterminded by the company Arcadis on behalf of Real IS. Unlike the vacant property in Düsseldorf, the building in Amsterdam was occupied and the collaboration with public-sector tenant Rijksgebouwendienst proved decisive for the successful completion of the process.

The Book is a modern, fit-for-purpose office built in 2004. The certification was meant to optimise the building and the building operation along economic and environmental lines.
A corresponding green seal was also supposed to enhance tenant relations and tenant loyalty while boosting the asset’s competitiveness for lease renewals and re-lettings.

Step one was to determine what certification level would be attainable. BREEAM In-Use was chosen, a system adapted to country-specific standards and regulations. Choosing the US label Leadership in Energy and Environmental Design (LEED) would have meant transcribing the entire documentation into the US measurements, standards and value system.

The selection of BREEAM was followed by the drafting of a road map and an action plan, based on a questionnaire submitted by the certifying body. The questionnaire was populated online by an independent, licensed assessor.

Key components of the in-use certification include the environmental report and data relating to the tenant’s use. Since The Book was able to present sound ratings, few aspects of the property required retrofitting upgrades. Among them was installing energy meters, replacing showerheads and fittings with water-saving ones. Information on public transportation was made centrally available to building users.

In the end, The Book obtained the BREEAM NL In-Use certificate with relative ease. This matches the experience with the K-LAN asset in Düsseldorf, which was awarded the DGNB Bronze certificate without having to subject its technical facilities to a complete overhaul. In both cases the main focus was on the documentation of user behaviour and consumer ratios.

Certification of buildings meeting similar criteria will probably increase as investor demand for such properties is high. Government tenants have come to consider green certification as key for renting, as have some large corporates. New buildings alone will not satisfy demand.

Jochen Schenk is member of the board at Real IS