Using the properties of wind to our advantage. How can one element in a building, like the facade, have a multitude of uses and benefits.
1. Computational Fluid Dynamics
Computers are used to calculate the interaction of liquids and gases with hard surfaces. Algorithms simulate turbulent flows among other flows. CFD software is used by NASA, missile manufacturers, airplane fabricators, and now architects. Physical modeling is defined by equations of motion, radiation, and enthalpy. Fluid occupies a volume but obviously cannot flow through a solid so it must be forced around. (red/hot colors indicate the flow being forces around a hard solid. Cool colors indicate a free-er flow).
This brings us to the Venturi Effect. As the cross-sectional area decreases, the velocity of the fluid increases. It is a jet effect that happens when a space becomes constricted and fluid pressure is reduced.
Laminar flow is calm and gently hugs a surface as it goes around it. Turbulent flow happens when there is a rapid variation in velocity and pressure, or other chaotic property changes. In my building, my facade directs wind flow into the building for natural ventilation. However, if wind gusts were too strong then the force of the wind would create turbulence on the outside of the facade. At the site located on the High Line in New York City, the wind flows mostly from the west and south over the course of the year. The wind speed is increased slightly in this area because of the breeze that come off of the Hudson River, which is to the west of the site. In plan, the wind is directed across the southern and eastern facades enveloping the building and ventilating through these sides as well as a partially open western facade. The wind speed reduces as it travels further between the facade and throughout the building.
2. Solar Shading Studies and Daylighting and the Building Envelope
One of my inspirations for the facade of this project was Ned Kahn and his structures “Microturbines” and “Articulated Cloud.” Both are highly influenced by the wind. The facade is made of the same material, which highlights the movement of the panels. http://nedkahn.com/wind.html
In my structure, my first concerns were about ventilation and the effects wind can have on a building and the atmosphere within. Then I varied the materials to consider light and the diffusion of light as well. Surfaces allow, partially allow, or block completely harsh southern light entering the building. Without the facade there would be drastic differences in temperature throughout the day. The facade acts as multiple layers that retain thermal energy as well as solar shading. Something I did not plan for but realized is that the facade allows for passive heating (although in New York I would still use mechanical systems for parts of the year). During the winter when the solar path is lower, direct sunlight steams in which in the summer the layered facade bounces the sunlight around and on most of the levels mostly indirect light is let in. New York City is at 40.7 degrees Latitude north. Therefore doing some math, The summer azimuth is 72.8 degrees and the winter azimuth is 25.8 degrees from the horizon.
lighting of building without facade:
With a facade there is protection from the elements as well as a strategy for which to use the elements.
Assessing the Building Envelope has many of the same finding as analyzing the daylighting conditions. My building has a double envelope, or for lack of a better term, a multi-envelope. The palimpsest of layers of material is highly logical based on the wind direction and sunlight. The interior spaces of the building respond to the facade in that interior art panels and walls only run north to south like the facade, continuing to regulate the flow of air. There are also many outdoor to indoor spaces where you experience the wildness of the wind flows taking their course through the facade. Again the material is important. The glass is tempered, meaning it was reheated then blast cooled for strength against bending, impact, and thermal stress. The glass ranges from 3/32″ to 1/8″ and it still lets in light because it doesn’t have reflective coating. Glass is a poor insulator however, hence another reason for the multiple layerings in the facade. The facade also has the ability to adapt where, instead of cladding on a column and spindle system, the panels can be employed by the wind to move. It would be possible to generate energy through the facade in this way but my initial intentions were for the experiential effects see from the inside as well as the High Line.
This short animation shows what one panel could be replaced with :