IV. Technology Opportunities in Major Building Subsectors
Technology opportunities and building system innovations for reducing
GHG emissions in homes and small businesses are similar.
In both cases, energy use
is currently dominated by a combination of space heating and cooling loads, which are principally a function
of climatic conditions. In contrast, energy use in large commercial and industrial buildings is generally
dominated by HVAC, lighting, and other internal loads and depends more on the type of business and
occupancy than on climate. Across all building subsectors, there is a growing trend to use green building
design, natural daylighting, recycled materials, and solar energy technologies for on site heat and power.
A. Homes and Small Businesses
An energy efficient building system must address two things: reduction
of heat flow through the building envelope and improvement in the efficiency
of all energy consuming equipment.
In the long run, integrated building systems in homes
and small businesses have the potential of requiring net zero input of energy through the incorporation of
solar hot water, photovoltaic systems, and other on site renewable energy technologies.
Building Envelope. The building envelope is the interface between the interior of a building and
the outdoor environment. The envelope separates the living and working environment from the outside
environment to provide protection from the elements and to control the transmission of cold, heat,
moisture, and sunlight to maintain comfort for occupants. Energy pathways through the building envelope
are traditionally divided into attic/roof, walls, windows, foundation, and air infiltration. Another important
category of energy consumption is the embodied energy of the building envelope itself.
The building's roof presents a large surface exposed to year round direct sunlight. The heat avail
able from this source is welcome during the winter, but summertime heat gains inflate air conditioning
loads. New reflective roof products address two shortcomings of current products. First, new pigments
Towards a Climate Friendly