Retrotec USACE - Manual (Page 131)

D1
Appendix D
Typical Waste and Ineffi ciencies
Waste and ineffi ciency are two terms often used similarly—sometimes
interchangeably—without clear defi nition. In this document, “waste” is
defi ned as an equipment or system (without regard for the equipment or
system’s energy effi ciency) operating when not needed. The term “inef-
fi ciency” as used here refers to the difference between the actual perfor-
mance of equipment (or a system) and its optimal performance.
D.1 Building Envelope Components
D.1.1 Walls
D.1.1.1 Poor Wall Insulation (Waste)
Excessive heat losses and gains due to walls’ low R-value result in increased
sensible load on heating and cooling systems. In humid climates, mold growth
may occur in air-conditioned rooms. Retrofi t insulation on concrete and ma-
sonry walls (Figure D1) can be internal and external. A retrofi tted building
will be more comfortable with lower energy consumption. When retrofi tting
is possible, external insulation should be used since it has many technical and
architectural advantages. Conditions are especially well suited for external
retrofi t insulation when the external wall is in need of repair or the existing
wall material no longer resists climatic demands such as rain and frost. Exter-
nal retrofi t insulation can be placed continuously on the wall surface so that
thermal bridges at the fl oor separations and on adjoining inside walls will be
eliminated. Internal retrofi t insulation is used where external retrofi t insula-
tion is not possible—e.g., in historic buildings. Retrofi tting insulation in walls
should be planned in connection with other energy-saving options. Attention
should be given to sealing air leaks around windows, improving or replacing
inferior windows (Figure D2) and insulation in other areas of the building
(attics). To obtain full advantage, it is often necessary to readjust the heating/
cooling and ventilation systems after the insulation and sealing work has been
completed. For more information, see “Retrofi t Insulation in Concrete and
Masonry Walls,” by Svein Erik Torgersen, edited by Knut I. Edvardsen. Alaska
Building Research Series HCM-01553, April 2005, original NBI: A552.312.