Fluted Vapour Stack: An example of the Ceramic Core Systems for Solar Heating and Cooling
Dan approached the design using technical constraints, specifications that are consistent with the Solaesthetic Ethos:
Create a product that is easily customised for site specific needs, and adapted for versatile uses Use low impact materials
Use highly durable and easily replaced materials
Use materials that can be adjusted to match local visual qualities
Use manufacturing techniques that are already existent and may be reproduced in the field
Make the product deliverable on a standard pallet and that requires standard trade/craft skills for installation
Design for retrofitting and new installation
The constraints were genetical rules – a framework for creative engagement with the technical problems and although the design process was constrained the resultant artefacts are definitely not.
Dan began by disregarding all but the functional principles of existing technological solutions and started examining physical process and the properties of materials with respect for how they could be used for cooling. Evaporation of fluids from porous materials naturally causes cooling in the evaporative surface and the air passing over it. The thermal energy is transformed into latent heat carried in potential by the vapour, the air humidity increases and the heat sensed on the skin is decreased. Optionally, cooling efficiency can be increased by extracting the vapour from the system by condensing to the fluid (like a refrigerator) and discarding the energy released in the process. All air-conditioning systems do this is some way or another.
The important factors for evaporative components are the surface area of the structure and it’s porosity, which also contribute to the surface area at a microscopic scale.
Materials that fit the design constraints and that provide a good set of properties for evaporative cooling are fired clay, charcoal, gypsum based stones and plasters and some fibrous materials.
Clay is the most versatile of all of these. especially when you consider the manufacturing side of the design criteria:
It is ubiquitous and each locality has clays with different properties, which will tend to be expressed in the local architectural tradition
The properties of clay can be altered and tuned with by adding inclusions or blending with other materials
Clay working as a craft form that exists in all parts of the world and there are high levels of sophistication in it’s use
Ceramics can be treated with oxides and glazes to produce almost any colour and texture
It is relatively cheap and relies on very low tech working methods
Almost any form is achievable in clay
It is a familiar material to building trades in most trades cultures
The next focus was in the forms. The functional factors that are necessary to include are surface area and porosity, The surface offered to the air for evaporation needs to be as large as possible so that large volumes of air can be cooled. He looked at how natural forms have evolved in organisms to maximise surface area in order to find forms that satisfy both functional and aesthetic needs. There are many examples of historic architectural uses of the evaporative principle, in particular, cooling urns, arabic wind towers (بادگیر bâdgir) and filigree screens that use flow and slight exothermic behaviours= all of these can be called on for the design.
Dan experimented with forms and searched out natural examples of form that could take advantage of multiple cooling principles. Evaporation rates are enhances by high surface areas and high porosity. It is also related to the rate of air flow across a surface. Draughts can be generated by using a solar powered chimney effects or convection effects. So hollow forms that have an internal chamber to direct air flows were selected that would behave in ways that optimise the evaporative effects. Interestingly, using forms that increase surface area for evaporation also has the effect of making them more effective at absorbing solar radiation and this provides an opportunity to make a device evaporator may be designed to also act as a collector. So we have a device that can be switched between cooling operation when it is hot, or to heating when it is cold.
Using long columnar structures offers a very large working surface area and is also, inherently sympathetic to a large variety of architectural contexts.
The next area of design considered methods of manufacture, construction and integration. Computer modelling and 3D printing allows ways of making unique forms and translating them into moulds and/extrusion plates very quickly. So it is very easy to offer a product in multiple forms and finishes that works by the same underlying functional processes.
Taken as a whole this approach gives a tremendous amount of creative freedom and versatility. Providing a large variety of aesthetic options that are technically viable and that can be easily adapted to meet a host buildings aesthetic requirements. Local visual cues and material qualities can be used to design versions of the ceramic components that carry an aesthetic response to the specific qualities of any particular built environment. The product thus becomes as much a design process as a product in itself.
Fluted Vapour Stack
“Fluted Vapour stack” is the first example of the Solaesthetic Research and Design’s Ceramic Core System and it is intended to offer a simple, coherent product that offers a versatile and popular air cooling and heating solution that is aesthetically suited to being integrated with a wide range of buildings. It is functionally very simple. It is the design and execution that is special.
The heating/cooling element takes the form of a hollow, fluted column with hemispherical caps at the top and bottom that terminate the form, like a long capsule like form. The forms are inspired by the growth structures in grasses and bones. These shapes are also informed by the ways in which corals maximise their surface area.
Several columns can be used in arrays to add capacity and or to make visual statements. As the are built of component modules, they can also be made to different lengths.
Almost all currently available air-conditioning units are ugly. Reason enough by itself to re-evaluate the design of air cooling systems to produce something that is attractive and visually sympathetic. Add the massive energy costs of running air-conditioning, it accounts for 16% of all energy use in the world and in areas this goes up to 30%. The need for architecturally sensitive, versatile and cheap to run alternatives seems urgent.
Inspiration for the ceramic column cooling element came from seeing decorative ceramic drainpipes in heritage towns like Carcassonne and Montpellier in the south of France, where richly glazed and playfully ornate downpipes are part of the backstreet vernacular that makes these places so beautiful. Another point of reference was the architectural methods used by ancient Arabic builders to create refrigeration using the arrangement of structures in relation to natural forces with no artificial power inputs, in conditions of extreme heat. The main thrust in the thinking behind the design was to look at the ways that nature transfer energies in non-technological ways and work up a design from there to provide for contemporary air cooling needs and expectations in aesthetically sensitive urban environments.
The columns are made up of semi-cylindrical pieces that stack on top of each other to achieve the desired height. The Column is fixed flush to the wall of a building and are connected to the interior via holes at the top and and bottom. All that is visible from the outside is the sculptural ceramic column.
In Cooling mode, The internal chamber is the evaporating chamber. The internal surfaces are highly porous and are kept moist. Warm air is propelled into the chamber and as it passes through it is chilled by the evaporative process. At the exit, air is cool and saturated with moisture. It is then passed through a PV powered, compressive distillation unit which extracts the moisture. The distilled water can be re-used, either within the system, or for something else e.g. irrigating a green wall which would enhance the cooling effect in external situations.
The cooled dried air is then ducted into the building where it is needed.
In Heating mode, the system is run dry as a simple air heater. Solar radiation heat the clay and this in turn heats the air inside. The design is not intended as a full solar thermal solution and is best specified as an assistive component to a true heating system.
This system can use purpose-built ducting or it may take advantage of existing HVAC ducting or it mat even contribute to a already installed HVAC.