Lecture 7

BASIC PRINCIPLES  +  APPROACH TO DESIGN

Reading:

A Green Vitruvius: p. 1-5, "Introduction" [The Imperative to Green Design; Architectural Quality; Quality of Service; Passive Solar Design (heating, lighting, cooling); Green Design (waste, materials, systems); Natural Resources; Urban Planning].

We, of the world’s architectural and design professions, commit ourselves to:

• Place consideration for environmental and social sustainability at the core of our design work

• Develop innovative practices, procedures, products, services, and standards that will enable us to implement such sustainable design

• Educate our fellow professionals, our clients, and the general public about the value and critical importance of sustainable design

• Work to change policies, regulations, and standard practice in government and business so that sustainable design will become the fully supported standard practice in the building industry

• Work to bring the existing built environment up to sustainable design standards.

— World Congress of Architects Declaration of Interdependence for a Sustainable Future, penned in Chicago in 1993 

DEFINITIONS:

Passive Energy Design:

Design considerations that are intended to heat, cool, and light without the necessity of external energy sources.

Active Energy System:

Systems that heat, cool, and light a building through the introduction of external energy sources, such as natural gas, electricity, coal, wood, etc. which must be purchased from suppliers.

Hybrid Energy Systems:

Combined Passive and Active Energy Design.

Most buildings are designed as hybrid combinations of passive and non-passive (i.e., active) energy systems.  For the moment we will consider passive energy only, so as to isolate them for clarity of understanding. 

But first, a reminder of basic principles and facts of fluid and temperature dynamics:

BASIC PRINCIPLES

• Simple principles we all understand, intuitively if not intellectually: warm air rises, cold air falls; fast moving air (wind or breeze) changes the temperature of that which it passes over more quickly than slow moving or still air; moist air holds heat more effectively than dry air, evaporation produces a cooling effect; moist air, when it comes in contact with something much cooler, loses moisture (condensation); mass materials have the capacity to hold heat (as a "thermal mass" or "heat sink"), then radiate it away when surrounding temperatures drop; cellular materials inhibit the passage of heat (insulative materials); light colors reflect away heat radiation and dark colors tend to absorb heat radiation; . . . and so forth. 

"Simple" evolved domiciles in disparate climatic settings are instructive as to the efficiency of their design with regard to human comfort.  The three examples here, for instance, though apparently simple ("low tech"), on close analysis are remarkably sophisticated.  Look at each with respect to what you know about the climatic conditions of its setting.

 Image courtesy of Norman Crowe

In addition to these there are plenty of detailed examples of the means to ensure comfort "naturally" throughout the world where traditional ways of building and traditional ways of living persist.  These are examples of achieving the maximum comfort with the greatest efficiency.  This includes landscape as a means to shading in the summer months, simple shading devises over openings in walls, heavy walls in the desert where the sun is both bright and hot while the nights are cool, or lightweight walls of low mass in the tropics where the nights tend to be warm.

Finally there is the condition of gravity ventilation, whereby the section properties of a building are the most critical with respect to cooling and heating.  (See the section foldout at the front of The Green Vitruvius).  This is also the situation when it comes to sun penetration.  Winter sun angles and summer require different conditions of shading and acceptance to the interior.

Examples of Gravity Ventilation Image Courtesy of Norman Crowe

APPROACH TO DESIGN

1. Design approach needs to be an inclusive/holistic/interrelated/comprehensive frame of mind.  That is to say, non-linear, and complex.  This is especially true in hybrid energy design.  The process is experimental throughout.
2. The frame of mind that approaches design as "green" assumes that it is not only economical and environmentally sensitive, but it has psychological advantages for the occupants of buildings as well.
1. We sense the relationship of the building to the environment of its setting.  Natural light and ventilation, produce variations throughout the day as opposed to the constancy of mechanical air-conditioning, heating, and lighting
2. Linear process instead produces the "black box" approach: seal the windows and control everything through sensors, forced ventilation etc.  Is this an unnatural environment?  Passive energy design is messy by comparison to linear engineering systems.
3. Formal (professional) design process
1. pre-design (program formation)
2. conceptual design (parti)
3. schematic design (proof-of-concept phase)
4. design development (analysis and production)
5. construction documents (contracts)
6. construction
7. building occupation (initial building operation)*
   *This phase requires learning how to manage the building.  With passive energy systems this is an important requirement because passive energy systems usually require attention throughout the cycle of day and of the seasons, often on an individual basis.
4. The cost of green design/passive energy measures (i.e., beyond code minimum) should be approached as long term investment as opposed to bottom line construction.
1. payback period, and
2. lower operating costs (and usually maintenance costs as well) reap the benefits once the pre-established payback period is past
3. a matter of principle as well, which enhances basic decisions.
5. Hybrid Systems
1. Designed as "collage"  Again, non-linear.
2. Always a task for the architect in consultation with engineers, and no longer the all too often approach of the architect designing the building based on a set of criteria that precludes natural ventilation, day-lighting etc., then turning the work over to the engineer to "integrate" mechanical and electrical systems.
3. Building operation can modify the relationship between active and passive systems to suit contingencies etc.

DISCUSSION SESSION

1. Discuss how and when each specific issue involved in green design may be logically introduced into the design process, including
1. waste management (both post-construction and during construction),
2. day-lighting,
3. selection of materials,
4. landscape design, and of course
5. passive energy techniques.
   You may base your discussion on your own design process as well as the more elaborately staged professional sequence involving a client.
   
          — or —
   
2. Consider the differences between traditional design and modernist inspired design.  How would you explain to a client/owner (or your employer, for instance) why passive energy techniques may be just as effective in traditional design as in modernist design, where "invention" is considered as a fresh start from the onset, thereby "avoiding the encumbrance of preconceived forms and ideas"?