Wildlife corridor Bakel

How the Ladder stimulates innovation and collaboration 

In tenders, the Aa and Maas water authority regularly uses the CO₂ Performance Ladder as an award criterion. This was also the case for a project to create an ecological connection zone in the east of the Dutch province North Brabant. The contractor, Van der Aa Brothers (Gebroeders van der Aa), was awarded the contract. Wim van der Aa and the water authority explain how the use of sustainable materials and a faster execution method reduced emissions, and why the use of the Ladder is more than just a tool for CO₂ reduction. “A Ladder certificate says something about the quality of a company and the values they pursue.” 

The Ladder as an award criterion 

Like other water authorities, the Brabant-based Aa and Maas works on a robust and climate-resistant water system. At the same time, the water authority strives to contribute to the fight against climate change by reducing greenhouse gas emissions. One way they do this is by incorporating the CO₂ Performance Ladder into their procurement, explains Mike Pepers, procurement advisor at Aa and Maas. “The Ladder is a way for companies to distinguish themselves not just by price but also by sustainability in their bid. In most cases, we choose to use the Ladder as an award criterion in a tender.” 

Partner with shared values 

By allowing companies to use their Ladder certificate in a tender, the water authority knows that organisations are actively engaged in CO₂ reduction, says Pepers. “It shows, among other things, that a company has sustainable equipment, has an accurate understanding of its own emissions and the emissions in its supply chain, and is working on reducing them. That they are doing this using a structured method says something about the quality and professionalism of the company. Moreover, you know you’re working with a party that shares the same ideals and ambitions. We find that very important. So, it’s more than just looking for a party that emits as little CO₂ as possible. We really want a partner that shares our values. And the Ladder helps with that.” 

Ecological connection zone 

One of the projects where the water authority Aa and Maas used the CO₂ Performance Ladder as an award criterion is the development of the Snelleloop stream – near the village of Bakel – into a more natural and robust watercourse. The project is part of the Bakel-Milheeze integrated area programme, which has been ongoing since 2005, says project leader Marjolein van den Hoven. “This project is, among other things, focused on improving water quality, in line with the goals of the European Union’s Water Framework Directive (WFD). Improving the ecological conditions in and around the stream leads to cleaner water, which benefits nature. And that nature, in turn, stores CO₂.” 

Nature-friendly banks and fish passage 

The project consisted of various elements, including the redesign of the Snelleloop stream with nature-friendly banks, the creation of ponds, planting of shrubs, and flower-rich grasslands. Thanks to these measures, the area has become more suitable as a habitat for amphibians, dragonflies, and shrubland birds, says Van den Hoven. “In addition, we wanted to promote fish migration with the installation of a De Wit fish passage at a weir and the replacement of another weir with a cascade fish ladder. This allows fish to move in both directions and swim more naturally. We worked out the project plan in a specification. Once that was ready, we issued the tender.” 

Combination of low price and certification 

By using the Ladder as an award criterion, parties could receive a fictitious discount on their bid price. All three parties that submitted bids were in possession of a Ladder certificate. Although a higher certification level means a higher discount, it was not the Ladder that made the final decision in this tender, says Pepers. “It’s about the bigger picture. In this case, there was a party certified at level 5, but their bid price was so high that the tender was awarded to a party with a level 3 certification: Contractor Gebroeders Van der Aa. So, in this tender, it was a combination of the low price and certification level.” 

Plastic instead of concrete 

After the award, Gebroeders Van der Aa could start work at the end of 2024. To minimise CO₂ emissions, the specialist in road and water construction focused on various aspects, says Wim van der Aa, who, along with his brother Driek, owns the family business. “One of these aspects was materials. For the construction of the cascade fish ladder, we used twelve screens made of hardwood. Hardwood has a long lifespan and is easy to maintain. For the basin of the fish passage next to the sluice gate, we used concrete, but the intermediate walls were made of plastic. The advantage of plastic is not only that it emits less CO₂ during production than concrete, but also that it can be precut. This allowed us to use a faster execution method and required less water pumping.” 

Less pumping means less fuel 

Van der Aa only needed to temporarily drain the stream for pouring the concrete of the slope. ” I designed the fish passage myself, based on a design from a previous project I did for the water authority. That project had already shown that this method was easier and faster, thus reducing fuel consumption for pumping water. I appreciated that the water authority gave me the freedom to contribute my own input. Ultimately, this benefits both sides. During the execution, we also had many consultations with the water authority, for example, on how to pump water more efficiently. The Ladder also encourages this kind of dialogue. Communication is very important.” 

Battery packs delivered too late 

A small setback in the project was that the battery packs Van der Aa had ordered were delivered too late and therefore could not be used. Van der Aa: “With those batteries, we wouldn’t have had to use a diesel-powered generator. That would have reduced emissions significantly because you can charge batteries with green electricity. To minimise emissions, we used a generator with a new engine and a soot filter. That way, we reduced the damage. Fortunately, we have received the battery packs now, so we can use them in the next project. And we definitely will.” 

Clean and emission-free construction  

According to Pepers, such setbacks do not immediately have consequences. “We specify the design in our specifications, but during execution, we don’t make specific agreements. An external auditor ultimately checks whether the party has met the requirements of the submitted ambition level. However, we do follow the guidelines of the Voluntary Agreement Clean and Emission-Free Construction (SEB). For example, regarding vehicles, the SEB sets stricter requirements periodically. Since early 2025, the EURO 6 / EURO VI emission standard is mandatory. This is also in our specifications, and the executing party must comply with it. Starting in 2028, this will be partially Zero Emission (ZE), with a goal toward fully ZE.” 

Balancing costs and sustainability 

For Gebroeders Van der Aa, investing in sustainable materials remains an important focus. However, the company must also consider costs. “We’ve been looking into purchasing an electric excavator for a while. The purchase price is very high, though. We are a relatively small company and need to have enough work to make such a machine profitable. If our costs go up, our bid price in a tender will also go up. And if other parties have a higher certification, it becomes harder for us to win the tender. Finding the right balance makes investing in sustainability quite challenging.” 

The Ladder more often in smaller projects 

Despite these challenges, Pepers sees that more and more contractors are using their Ladder certificates, even in relatively small projects. “In the SME sector, companies can still really distinguish themselves with having a certificate and its level. For larger companies – which often do bigger projects – it’s much harder to make a difference with certification because most of them are already at the highest level. What I also find nice to see is that the companies we work with are truly proud of their Ladder certificate. It’s more than just a tool to win a tender. It really sets something in motion within a company. That’s what makes it valuable for us to continue using the Ladder in our procurement.”

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