| |
Set-up
|
Commissioning |
| 1.
Roof/ceiling marriage line sealed with approved backer
rod, caulk or foam. |
_________ |
|
| 2.
Floor marriage line inspected to insure integrity, and
repaired if necessary. |
_________ |
|
| 3.
Wall marriage line inspected to insure integrity, and
repaired if necessary. |
_________ |
|
| 4.
Wiring and duct penetrations are sealed. |
_________ |
|
| 5.
24/7/365 programmable thermostat is properly programmed.
|
_________ |
|
| 6.
Heating/Ventilation duct dampers are opened to the 100%
open position or set to design specifications. |
_________ |
|
| 7.
A complete maintenance and operation manual is provided
to the school facilities manager. |
|
_________ |
|
8.
Outside fresh air supply is tested to insure a minimum
of 15 cfm per designed number of occupants. |
|
_________ |
|
9.
Ventilation exhaust system is tested to insure the designed
flow rates are provided. |
|
_________ |
|
10.
HVAC system air flows are tested to insure that all
designed air flows are met. |
|
_________ |
|
11.
Occupancy controls are installed and operating to manufacturer's
specs. |
|
_________ |
|
12.
Duct flow measurements are tested and the duct system
is balanced to ensure even flows from each diffuser
and grill. |
|
_________ |
Purpose:
To ensure the most energy-efficient operation of existing
portable classrooms by providing efficient and cost-effective
envelope, air sealing and control measures. Implementation
of these guidelines will help ensure lowest life cycle costs,
maintain acceptable indoor air quality and comfort standards
while providing a suitable learning environment.
These
guidelines have been developed with support from the US Department
of Energy's Building America Program partners and the Oregon
Office of Energy, the Idaho Energy Division of the Department
of Water Resources and Washington State University Energy
Program.
Additional
information is available at:
Technical
assistance regarding these guidelines is available from:
-
Washington State University Energy Program - Michael McSorley:
(360) 956-2008
- Idaho
Department of Water Resources, Energy Division - Bob Minter:
(208) 327-7970
- Oregon
Office of Energy - Betty Merrill/Justin Klure: (503) 373-1581
Introduction:
The decision to retrofit an existing portable classroom
with energy-efficient measures is a complex one. While the
lack of energy-efficient envelope measures may result in costly
utility bills and comfort issues, the cost of installing most
measures will likely not be cost-effective. There are specific
instances where it makes sense to retrofit:
In
the event of a portable classroom that is scheduled for removal
and demolition, retrofitting the classroom may be extremely
cost-effective, in that the cost for retrofit is much less
than the cost for disposal.
In
the event that building components are replaced, they should
be replaced with the most energy-efficient possible.
There
are specific measures that are always cost-effective, or are
cost effective in most situations.
Table
1 lists the potential retrofit measures for portable classrooms,
and identifies instances where retrofitting the building component
may be appropriate. Details for specific measures are listed
below the table.
Table
1. Recommended Portable Classroom Retrofit Specifications
| Component |
Description |
Component
U-factor |
Nominal
R-value |
Recommended |
| Envelope
Measures |
| Ceilings
|
T-Bar
Ceiling |
U-0.033 |
R30 |
When
existing insulation is R-11 or less, or if insulation
is replaced |
| |
Rafter |
U-0.033 |
R30 |
When
existing insulation is R-11 or less, or if insulation
is replaced |
| Walls |
4
inch |
U-0.077
|
R13 |
If
siding is removed or insulation is replaced |
| |
6
inch |
U-0.053 |
R19 |
If
siding is removed or insulation is replaced |
| Floors |
Joists |
U-0.041 |
R30 |
If
insulation is replaced |
| Glazing |
|
U-0.371 |
n/a |
If
glazing is replaced |
| Skylights |
|
U-0.51 |
n/a |
If
skylight is replaced |
| Exterior
Doors2,3 |
|
U-0.19 |
n/a |
If
door is replaced |
| Air
Sealing |
| Penetrations
in building envelope |
All
penetrations caulked or otherwise sealed to limit air
leakage (see detail below) |
As
appropriate (see detail below) |
| Mechanical
Systems |
| HVAC
control |
The
HVAC system shall be controlled by a 365-day programmable
thermostat equipped with an occupancy sensor for ventilation
system control. |
In
all cases. |
| Lighting |
All
interior ceiling lighting shall be rapid start T-8 fluorescents
with electronic ballasts with a CRI of 75. The controls
shall be an on-off switch for each bank of lights. |
If
fixtures are replaced |
1NFRC
tested U-factor
2Door
frame shall be of thermally improved material(s).
3Up
to 1 ft2 of security glass is allowed in doors.
Glazing
and skylights
As
the total square feet of windows is usually small in most
portable classrooms (approximately 48 ft.2), it
is not cost-effective to replace old windows unless seals
have failed, admitting moisture from the exterior.
Penetrations
through building envelope All
penetrations shall be caulked or otherwise sealed to
limit air leakage, including the following:
- All
window and door frames - sealed to the building
envelope.
If the seal is made on exterior grooved siding, then the
groove lines shall be sealed at the door or window frame.
- Exterior-wall
sole plates and the structural floor - caulked
using silicon caulking or approved alternate.
- All
receptacles, switches or other electric boxes in exterior
walls - sealed or fitted with outlet plate gaskets.
- HVAC
ducts - sealed at interior surfaces where ducts
penetrate the building envelope.
- Around
openings in the building envelope for HVAC and ventilation
ducts, and wiring.
- All
other penetrations in the building envelope.
Ceiling
air barrier
Most
of the portable classrooms built after 1990 do not use sheetrock
ceilings; rather, they incorporate a T-bar dropped ceiling
with tiles. This type of ceiling typically has no air sealing
to control air leakage, and represents a major source of heat
loss from the classroom.
To
combat this heat loss, a 4-6 mil polyethelene air barrier
shall be installed above the ceiling tiles and below the insulation.
All penetrations through this air barrier shall be sealed
with silicone caulking; the same shall be done for any overlaps
and the perimeter of the air barrier.
Portable
classrooms that have the ceiling insulation installed in the
roof rafters shall have the air barrier installed under the
insulation, stapled to the roof rafters, and sealed with caulk
at the edges.
HVAC
Control
Most
of the portable classrooms in the Northwest region are controlled
by 7 day programmable thermostats. The result of this type
of control is that the HVAC system operates throughout the
year, even during holidays and vacations. Even new units
that were installed during the study exhibited this behavior.
In
addition, many portable classrooms are controlled by CO2
sensors. The BAIHP study determined that CO2 sensors
can be unreliable as a control strategy, since they go out
of calibration easily, and many HVAC installers and school
maintenance personnel do not have the proper equipment to
calibrate them.
New
low-cost, 365-day programmable thermostats are available,
with occupancy sensor control for the ventilation system;
they are highly recommended for all portable classrooms, regardless
of age. Estimated simple payback for these thermostats is
2-3 years.
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