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Monday, June 1, 2009

Do Horizontal Farms on Buildings Make More Sense than Vertical Farms? Paul de Ruiter Thinks So

by Lloyd Alter, Toronto

Zuidkas exterior perspective image
all images courtesy of Architectenbureau Paul de Ruiter

We do go gaga over vertical farms, but they might be just intellectual exercises rather than serious solutions. As Adam Stein noted, talking about New York: "Local food has its merits, but that’s what New Jersey is for.” But there is a middle ground between "fetishist temples of food production" and New Jersey- using the real estate on our roofs. As Sami noted in another post, greenhouses work very well.

That is why I like The Zuidkas, a proposal by Architectenbureau Paul de Ruiter commissioned by the Government Buildings Agency in the Netherlands. It integrates a greenhouse into the roof. And by integrating both office and residential functions into the same building, the greenhouse serves the additional function of being part of a system of air and water purification. Talk about local food- you just go upstairs.

Zuidkas aerial perspective image

In most cities it would be hard to find a spot where you get sun on the sides of your building all the time downtown, unless you happen to be on an island like Manhattan. Putting greenhouses on the roof make a lot of sense when you are surrounded by other buildings, which is your typical urban solution.

Zuidkas section image

It also makes sense to develop a mix of uses; their energy uses peak at different times. Paul de Ruiter explains:

The merging and advantageous stacking of offices, homes, a school and retail facilities results in a compact model. By including functions with a low-rise typology like stores and greenhouses in the model, the design makes optimum use of the available land. And thanks to the concentration of activities, there is less traffic than would be the case with a building with separate functions.

This compact model also creates an opportunity to develop a more balanced response to the demand for energy over time. In residential units, the energy demand spikes in the mornings and evenings. In the case of offices, the energy demand reaches its highest point at the middle of the day. A building’s energy supply often does not work efficiently, because capacity is regulated to meet the peak-hour demand any time of day, including off-peak hours.

Zuidkas details image
click on image to enlarge to almost readable size.

The design includes a glass shell that covers the configuration of the ground level and naves, creating a variety of climate buffers, that will work as an intermediate zone that naturally tempers the effects of the outside climate. The shell surrounding the building strongly reduces the surface area responsible for the loss of heat during the winter and cold during the summer. The buffer area facing south functions as a sun lounge for the homes. Thanks to the buffer effect, the loss of heat in the winter is reduced. In the summer, the sun lounge cools the adjacent areas thanks to the stack effect. In this process, fresh air is sucked in and constantly circulated. It will be possible to open the exterior shell, to prevent the area behind the shell from becoming too hot.

Zuidkas model image

Another reason to build the offices facing north is the extremely high production of internal heat by computers, lighting and appliances (and their users). This results in a fairly substantial cooling requirement in the summer period. By building the offices facing north, the heat of the sun in the summer has less of an impact on the building, with less energy required to cool the building as a result.

Zuidkas interior image

In homes, the production of internal heat is far lower, and the average temperature is often higher. By building the homes facing the south, and including a terrace, the design can actually make use of the heat of the sun, which in the winter makes a major contribution to the supply of heat.


The mix of uses creates waste that is used to produce heat and electricity.

Besides vegetable waste and biomass from the greenhouse, the building will also collect black water (toilet water) and lead it to the co-fermentation plant. In the co-fermentation plant, all biomass will be converted into biogas. This gas will serve as a sustainable fuel for the CHP power installation (bio-cogeneration). The heat that is released in this process will be used to heat tap water as well as the various building areas. Besides generating heat, the CHP power installation will also produce high-quality energy in the form of electricity.

The heat surplus in the summer and the cold surplus in the winter will be stored via a geothermal storage system in thermal masses below the surface. The stored heat will be used in the winter and the stored cold will be used during the summer. The supply and consumption of heat and cold will become even more interesting as an option if the whole surrounding area is involved in the geothermal storage system.
Rainwater will be collected on the roof. The quantity collected – some 4,130 m³ per year – is more than sufficient to supply the greenhouses and flush the toilets. The remainder of the collected water can be used for the washers and various household activities.

Zuidkas facade perspective image

I think there is a lot to be said for this concept, as a good compromise between the fantasy of vertical farms and the desire for local green in urban areas. It all works together symbiotically, producing food, cleaning air, generating power. The roof becomes a real productive part of the building, part of a system.

Thanks for the tip to Architectenbureau Paul de Ruiter

UPDATE: They have a website with more information on the project.


Client Government Buildings Agency
Design April-June 2008

Design Architectenbureau Paul de Ruiter
Design team Paul de Ruiter, Chris Collaris, Haik Hanemaayer, Noud Paes, Marieke Sijm

Advisor Arup Amsterdam: Jaap Wiedenhoff, Christa de Vaan