Advanced use of water to provide a cool micro-climate around buildings in the 21st century
Cool water. From the earth, into plants. Onto the plant’s leaves; evaporating and providing cool air. “Dagmar”. A historical name, connecting Denmark and Russia. The Empress Maria Feodorovna of Russia was Princess Dagmar of Denmark before her marriage in 1866.
She laid the current garden in the inner courtyard of the Winter Palace—and the trees are now tall, allowing the possibility of enhancing the cool micro-climate there. Perhaps such trees are not appropriate for some architectural styles, but they certainly allow the possibility for a very advanced, yet simple, form for stabilizing the indoor climate of the Winter Palace.
Water is necessary for life, but is paradoxically often a problem. In cities: rain and snow on rooves, in drainage systems, overflows and floods. In buildings: high moisture levels are regarded as the source of many indoor climate problems, house dust-mites, fungi, giving asthma and allergies.
But turn the problem inside out, and harness the beneficial properties of moisture in construction, and suddenly climatic regulation has a friend.
How is this appropriate to The Hermitage Museum? Well, quite simply, this “biological air-conditioning” can create micro-climates in the courtyards of The Hermitage that are cooler and cleaner in summer than the surrounding air, and this cool clean air can be drawn into the rooms of the Winter Palace by selectively opening windows, and other ventilation system inlets, that face onto the courtyard.
In fact, all ventilation system inlets, many currently at street level facing the busy Neva Embankment, should be relocated to face the cool, clean courtyards.
An additional benefit is that the cooled air from the trees will fall to the ground, drawing fresh, clean air down into the courtyard from above. This flow of cool air will enhance the cooling effect (a system called “summer breeze design”, which I used at the Danish Pavilion at the world EXPO in 1992).
Visitors entering the courtyard through the main gates will be met by a cool breeze on even the warmest and stillest days. And it will be self-regulating—the warmer the day is, the more evaporation will occur, and there will be an increase in the quantity of air and a decrease in temperature.
It is not just a question of temperature. Drawing aggressive exhaust fumes from vehicles into the Winter Palace rooms is harmful to the artworks (not to mention humans): diesel exhausts include volatile organic chemicals, extremely aggressive to paints and varnishes.
It is well known that forest air is cool and clean, and this factor can be used, and has been used for thousands of years, in building design, a link between the landscape and the building.
Trees and plants are, hydro-dynamically speaking; biological water pumps, taking water from the ground up to their leaves, for the prime purpose of photosynthesis, but also to protect the leaves from the sun by cooling them by evaporation.
Evaporation, as also explained in the section “Palladio” concerning evaporation from inside wall surfaces, is an enormously effective method for energy transfer.
On the inside of the buildings, surface materials elegantly harnessing evaporation use the diffusion principles: Rococo air-conditioning? Here named “Palladio”.
Outside the buildings, plants are just as naturally using evaporation of water to cool themselves and the surrounding air. Biological air-conditioning? Here named “Dagmar”.
Technically, evaporation of 0.2 liters of water provides the same amount of cooling as one liter of water cooled from 100 degrees to 0 degrees, or 40 cubic meters of air cooled by 10 degrees.
Think of this please. 50 grams of water, a small vodka glassful, has the latent energy to cool 10 cubic meters of air from 30 degrees to 20 degrees.
And all this without any complicated mechanical devices to pay for, to maintain, to constantly supply with expensive electricity, to hear!, to find space for, to replace after 20 years—more expense!, more unsustainable “growth”.
No. Evaporation gives simple cooling: a gift of nature, from God. And to make it even easier, God has given us water pumps, taking moisture from the ground high up into the air; trees and plants. In simple words, evaporation of small amounts of moisture is enormously effective for keeping things cool.
This is of course why, in warm climates, traditionally, a large clay pot filled with water and placed in a window is an effective air cooler. Or a moist clay pot over a milk jug, a milk cooler, as my mother used in Italy in the 1930s. Of course, a refrigerator is an appropriate use of modern cooling technology, and there are also situations when room cooling by mechanical air-conditioning is necessary.
But this choice should be analyzed carefully, and, most importantly, if sufficient attention is paid to the building itself, the necessary equipment to supplement the cooling, heating or ventilation requirement will minimal, resulting in considerable economic, climatic, and ethical benefits. This is in fact the main message of these papers.
At the world EXPO in 1992 in Sevilla in Spain the hosts extended the above principles with appropriate application of quality modern technology. The main avenue of the exposition was lined with trees, so the Sevilla engineers placed a small water pipe running from branch to branch along the avenue high up in the crown of the trees, with small nozzles that sprayed a fog of water onto the surrounding leaves.
Tremendously effective, providing a delightful micro-climate for the visitors, and a fine example of combining old and new technologies.
In the Inner Courtyard of the Winter Palace is a pond with a fountain, in the middle of the garden with tall trees. It would be a simple matter to combine the fountain with the proposed cooling effect by pumping some water up into the tree tops to spray the leaves to both clean and cool the air.
An additional option, as is common in South American cities, is spraying water onto the paving stones in the afternoon. This both cleans the streets and cools the surfaces. Remember also that the River Neva runs on the Northern side of the Winter Palace.
This cool air would be beneficial for both visitors queuing at the entrance and as a source of cool, clean air for the ventilation of the rooms, both directly through windows facing the courtyard, and indirectly, through fresh air intakes of the ventilation systems.
Plants also have other properties of interest to building physics.
During photosynthesis plants absorb carbon dioxide and emit oxygen. A useful feature in rooms with many people, because people absorb oxygen and emit carbon dioxide.
Some avant-garde architects are using plants extensively in indoor hanging gardens.
The American space agency NASA have researched plants for their chemical cleaning properties, and found, amongst other things, that the Ivy plant absorbs and converts the chemical formaldehyde, which is harmful to humans.
All in all, plants and water can, and I would suggest the word “should”, be used actively to assist climatic regulation of buildings. This integration between landscape architecture, buildings, and climatic control, is not new, but is nevertheless not much used, and has not yet been developed into a 21st century consciousness.
The name “Dagmar” for this feature is suggested, but other more descriptive names can probably be found. For the purposes of this leaflet, addressed to Russian students, “Dagmar” indicates a link between Russia and Denmark, like this project.
St. Petersburg is a very appropriate city for developing old concepts, such as “Dagmar”, in a new framework. The minimalistic climatic regulation method used in some areas of the Winter Palace, developed by Danish and Russian people, together, is probably applicable to many other historic buildings. It is possibly also a useful method for other types of building, both new and old, also in other climates.Sergio Fox