Lecture 8

"The Building Envelope: Check List for Ongoing Projects"

Reading:

A Green Vitruvius: "Envelope," p. 63 – 75, and "Life Cycle Cost, p. 140 – 141.
(note that the portion of this reading assignment on building envelope has been assigned earlier).

Though modern buildings have made living easier for millions, they have also resulted in more subjective problems.  Traditionally, local materials and the demands of climate tended to give each indigenous architecture a distinctive character.  What shapes modern buildings are the abstract theories of academic architects, the careful calculations of corporations and developers, and the short-run economics of the highly competitive building industry.  The result everywhere has been monotonous business and commercial neighborhoods mixed with garish commercial strips.  These buildings rarely offer visitors a sense of connection to the fabric of a place, or, by extension, to a community…. If the aesthetic freedom granted by industrial materials and fuels carries with it a certain responsibility, then designers and builders have often been derelict in their duties—not just to the natural ecosystems from which life is drawn, but to the people who live and work in their creations.

      — Nicholas Lessen and David Roodman [from "Making Better Buildings", in State of the World: 1995, Lester R. Brown, ed., The World Watch Institute and W.W. Norton, 1995, p. 94-112]

The following items are listed for your consideration concerning on-going design projects.  They pertain to mostly formal characteristics of the building envelope.

Fenestration

Modification of fenestration based on orientation (solar gain, shading, utilization of heat-sink properties of materials, prevailing cooling breezes and winter winds, views, architectural expression, traditional patterns.

Thermal Bridging 

Avoidance of thermal bridging by means of thermal breaks in detailed window sections as well as in roofs and exterior walls.

Cool Roofing 

Reflectant (light) surface color, air circulation between layers (with "out-vent" at highest point), "green roof" condition with planting that approximates natural terrain.

Embodied Energy. 

Low embodied energy in materials and assemblies: Where did the constituent materials come from and what was the environmental and social impact at point of extraction; How was the material transported from place of extraction to places of manufacture and to the construction site, and what was the environmental impact of this transportation; What is the long term maintenance required; and finally, how long will the material and assemblies last in place, and when no longer useful, what are characteristics for recycling? This is perhaps the most overlooked, but important, characteristic for consideration in overall design criteria.

Note: For further embodied energy considerations, see "Life Cycle Considerations" below.

Insulation

Placement as near to outside of wall as possible or practical; consideration of alternative materials (non-VOC foam, extra thick "standard" types such as batts, and special consideration for recycled materials).

Overall Section Properties 

Atrium and other sectional features that promote natural (gravity) ventilation, permit and control solar gain (in combination with heat sink when appropriate); day light and natural ("outdoor-like") characteristics in the center of the building, especially in circulation and gathering spaces; glazed sun spaces, especially on south elevations.

Double Wall Envelopes 

All-glass secondary wall with ventilation between inner and outer layer, or traditional wall with oriel windows, glazed sun space, glazed loggias and attached sun spaces.  (Based on thermal siphon effect, with bottom to top openings for venting, specific to compass direction of exposure, materials of inner and outer walls, and adjacent interior spaces and exterior adjacencies).

Overall Building Footprint 

"Thin versus thick sections, based on the assumption that all occupied interior spaces are located with one or wall as an exterior wall (exceptions are storage rooms, mechanical equipment rooms, workrooms that are only occupied briefly, and restrooms).

Life Cycle Considerations 

Long lasting materials; low embodied energy (see "embodied energy" above), renovation-able materials or recyclable materials if disassembled for re-use;  pre-determined pay-back period for each material and component (see examples below), low maintenance, social impact of materials and assemblies with respect to procurement, manufacture, construction, and on-site (in-place) conditions.

Examples

The following illustrations are from previous years in this course, in response to a similar assignment to the one you are now completing:

DISCUSSION SESSION

1. Consider your current studio design project.  In terms of "green building design", what are its strengths and its weaknesses?  How may those "strengths" be amplified, and how may the "weaknesses" be mitigated? 
2. Be prepared to discuss the problem of "compromises" with respect to conflicting building requirements.  Examples may be:
1. if important views from the interior are in a direction that that receives the warmest sun late in the day (direct west-facing, for instance) in the summer;
2. if the ideal fenestration pattern for a street-facing facade would not meet optimum shading requirements for high summer sun angles;
3. if the optimum placement of important spaces/rooms does not permit gravity ventilation to take place "naturally";
4. if the building footprint is very deep, yet it is too narrow, (as may occur if it is located between party-walls), to permit the inclusion of an atrium-type space that admits natural light at the center of the building and encourages gravity ventilation.
3. Be prepared to discuss one or two of the above "compromises", plus one or two such situations you have encountered in your own designs.