When available, up-to-date floor plans, elevations and detail sheets define architectural geometry, establish orientations, provide dimensional information and specify construction detail. If a set of plans is not avail-able or if the plans no longer represent conditions at the site, sketches of the existing construction are used to record the information required for the load estimate.
These sketches are drawn to scale or accurate dimen-sions are added to drawings that are not to scale.
Sketches also provide an efficient way to record the information that is read from a set of plans. The collec-tion of sketches and notes shall provide the following information.
Sketches based on plan take-off or field observation
n An arrow or directional rosette that points north.
n A dimensioned outline of the floor plan for each level.
n The location of stairwells, partitions, chases and cavities.
n The length, width and height of every room with the room name.
n An alphanumeric code (WN-1, WN-2, etc.) next to each type of window or glass door.
n An alphanumeric code (S1, S2, etc.) next to each type of skylight.
n An alphanumeric code (DR-1, DR-2, etc.) next to each type of wood or metal door.
n An alphanumeric code (CL-1, WL-2, FL-1, etc.) next to each type of ceiling, wall or floor.
n Room assignments for occupants, appliances, lighting, plants and equipment.
Record observations pertaining to:
n The type of ceiling, ceiling construction detail (preferably with a Manual J construction number and overall R-value), the ceiling height (at the wall
or at the wall and ridge), the type of space that is above the ceiling (include detail that will help determine the temperature in enclosed, uncondi-tioned spaces); the type of vapor retarder; the air leakage that might occur at hard-wired lighting fixtures and ceiling penetrations, and the quality of the sealing and caulking effort at the top plate.
n The use of a radiant barrier under an attic roof,or encapsulated foam attic (if applicable).
n Attic vent locations, vent areas and powered attic ventilation equipment.
n A record of the location, size and type of skylights (preferably, with a Manual J construction number).
n Wall construction detail (preferably with a Manual J construction number and overall R-value), wall heights, the type of space that is on the non-conditioned side of a partition (include detail that will help determine the temperature in enclosed, unconditioned spaces); the type of vapor retarder, the type of infiltration retarder, the potential for leakage around electrical outlets and wall pene-trations, and the quality of the sealing and caulk-ing effort at plates, headers, sills, band joists and rough openings.
n The location, type and size of the window and glass-door assemblies and wood and metal glass-door assem-blies, with notes pertaining to U-values, SHGCs, construction details, bug screens, sun screens, projections and tightness.
n Internal and external shading devices and overhangs.
n The type of floor, floor construction details (pref-erably with a Manual J construction number and overall R-value), the type of space that is under the floor (include detail that will help determine the temperature in enclosed, unconditioned spaces);
the type of vapor retarder, the leakage that might occur at floor penetrations, and the quality of the sealing and caulking effort.
n Observed pathways that connect the conditioned space with an attic space, stud space, chase, crawl space or basement.
n The location of the appliances, display lighting, ceiling fans, waterbeds or any equipment that generates internal loads.
n The location of vents and exhaust equipment, with observations pertaining to the use of back draft dampers.
n The location and type of combustion equipment and fireplaces, with notes pertaining to the source of combustion air, type of vent or chimney and the use of vent dampers.
The preceding list applies to load estimates, but there are other items that should be noted during the survey.
(U-value and SHGC) for window assemblies and slid-ing glass door assemblies. Rated values are preferred because they eliminate uncertainty about window and glass door performance. When such information is not available, use the Table 2A values.
Also record the following information:
n The direction the glass faces
n Type of window (see Figure A5-11)
n The number of lites (panes) in the assembly
n The type of glass used in the assembly
n The frame material
n Frame conduction path (thermal break or no ther-mal break)
n The use of a storm window
n The type and color of internal shading devices
n The shading coefficient of external shade screens (when applicable and available)
n The X and Y dimensions (see Table 3E-1) of exter-nal overhangs (when applicable)
In regard to opaque doors, record observations pertain-ing to style (see Figure A5-12), construction material (wood or metal) and insulation. If a door has a rating label, record the tested U-value.
Also evaluate the tightness of the window and door assemblies. Collect data pertaining to tested leakage rat-ings — as listed in the manufacturer’s performance data, documented by the NFRC directory or displayed on a performance label. If quantitative information is not available, make notes that summarize the findings of a site inspection. Also try to evaluate the seal between the structural framing and the frame of the window or door assembly.
Ceilings
Ceiling performance depends on the type of construc-tion (attic, roof-ceiling sandwich or ceiling on exposed beams) and the construction details associated with the ceiling assembly (or attic knee wall). Ceiling and attic knee wall performance is also depends on the tempera-ture in the attic, which depends on the roofing material, the roof color, the use of a radiant barrieror encapsulat-ing foam, and the amount of attic ventilation. Such observations are used to select a construction number (see Table 4A), to evaluate structural tightness and to estimate resistance to moisture migration. Record the following information:
n Type of construction (attic, beamed or roof-ceiling)
n Size and type of framing
n Primary insulating material (type and R-value)
n Secondary insulating material
n Overall R-value of the attic-ceiling, parti-tion-ceiling or roof-ceiling assembly
n Type of roofing material (shingles or tile with air space)
n Long-term roof color and texture
n Details pertaining to attic ventilation
n The use of radiant barrier in attic (when applicable)
n Description of an unconditioned space above a ceiling
n Secondary insulation (sheathing material and R-value)
n Type and quality of vapor retarder
n Sealing effort at seams, light fixtures and penetrations
n Sealing effort at partitions, wall cavities, chases and stair wells
Skylights
For generic skylights, use qualitative observations and Table 2A to determine the U-value, SHGC value. Use Table 3C for the cooling HTM value.
Table 3D (-1 through -4) procedures apply to all types of skylights. Always try to obtain the NFRC rating (U-value and SHGC) for skylight assemblies. Rated val-ues are preferred because they eliminate uncertainty about window and glass door performance. When such information is not available, use the Table 2A values.
Also record the following information:
Figure A5-12
Sliding Glass Door
French Door
Wood or Metal Panel Door
Worksheet E Infiltration Loads
HTD = CTD = Design Grains = Elevation = Table 10A ACF =
Step 1 — Table 8 Outdoor Air Requirement Operating
AGV for each level = Floor area X Average ceiling height The above grade portion of a conditioned basement is one level.
AGV = Total of the volumes for all levels Default Occupancy = Number of bedrooms + 1
Furnace input defaults:
Direct Vent = 0 Btuh Atmospheric = 100,000 Btuh Recalculate, using actual input Btuh, if the total heating load exceeds 80,000 Btuh.
Cfm @ 0.35 = 0.35 x AGV / 60
Cfm for people = 20 x Number of people Cfm for Burner = 0.50 x Input Btuh / 1,000 Table 8 OA Cfm = Largest of the three Cfm values.
Cfmoadetermined by code requirement or designer decision to use the Table 8 OA Cfm value.
Step 2, Option 1 — Table 5 Defaults Operating
1) For default estimates use Table 5A or 5B to find ICFM values for the conditioned space and fireplace.
2) The component leakage area method or the blower door method may be used to estimate ICFM values.
Total ICFM = Space ICFM + FP ICFM Space ICFM = ACH x AGV / 60 Use the AGV from the Table 8 procedure.
T8 vent-CFM = T8 OA CFM - Cooling ICFM If cooling ICFMis greater than T8 OA CFM, the T8 vent CFM is zero.
Step 2, Option 2 — Component Leakage Area Method Operating
Table 5D ICFM Table 8
OA CFM
Table 8 Vent Cs Shielding CFM
Class
Cw
Heating Cooling
Default heating season velocity = 15 MPH
Default cooling season velocity = 7.5 MPH Detail from Worksheet
E1 ICFM = ELA4 x ( Cs x TD + Cw x V2 ) 0.50 T8 vent CFM = T8 OA CFM - Cooling ICFM If cooling ICFMis greater than T8 OA CFM, the T8 vent CFM is zero.
Step 2, Option 3 — Blower Door Method Operating
Table 5D ICFM Table 8
OA-CFM
Default heating season velocity = 15 MPH
Default cooling season velocity = 7.5 MPH Provided by
field test ICFM = ELA4 x ( Cs x TD + Cw x V2 )0.50 T8 vent-CFM = T8 OA CFM - Cooling ICFM If cooling ICFMis greater than T8 OA CFM, the T8 vent CFM is zero.
Step 3 — Infiltration Loads on Central Equipment Type of
The room infiltration load equals the load on the central equipment multiplied by the gross wall area ratio (WAR).
WAR = Gross room wall area / Gross wall area for all rooms served by the central equipment
eight-hour period beginning at 11 am and ending at 7 pm, standard time.
n This aggregate value is used for all roof-ceiling construction, regardless of exposure direction or time of day.
These averaging rules are applied to five types of wood deck roofs (ASHRAE Group 2, 5, 7, 10 and 13). The resulting collection of 8-hour averages are summarized by Figure A12 -13. (This figure lists base-case CLTD val-ues, which means they are compatible with a 20oF tem-perature difference and a medium daily range.) The HTM value for a specific type of construction is obtained by multiplying the appropriate CLTD value by the panel U-value:
HTMpanel= CLTD x Uceiling Ceiling Under Attic
The cooling load temperature difference for an attic ceiling panel depends on the attic temperature, which depends on the amount of insulation above the ceiling, the amount of attic ventilation, the use of a radiant bar-rier, encapsulating foam, attic fan, or extra attic vent area, and the type of roofing. Since the absorptivity and emittance of roofing products may not be known, roof-ing is classified by material (asphalt shroof-ingles, wood shakes, tile, slate, concrete, metal, membrane or tar and gravel) and color. The attic temperature also is affected by attic duct runs, but the temperature moderating effect is conditional, so it is (conservatively) ignored.
Figure A12-14 (next page) summarizes the attic temper-atures used to generate CLTD values for ceilings under an attic. These values are for the peak (late afternoon) load condition. They are used to estimate ceiling loads for all Manual J applications.
Ceiling on Exposed Beams
The cooling load temperature difference for a ceiling on exposed beams depends on the type of deck material, the thickness of the decking, the amount of insulation in the deck sandwich, the type of roofing and color. Fig-ure A12-15 (ahead two pages) summarizes the base case CLTD values for deck-on-beam construction. These values represent the average ceiling load condition that occurs during the afternoon. They are used to estimate ceiling loads for all Manual J applications.
Roof-Joist-Ceiling Sandwich
The co o l i n g l o a d te mp er atu r e di ff er en c e f o r roof-joist-ceiling sandwich depends on the type of deck material, the thickness of the decking, amount of insula-tion on the deck, the amount of insulainsula-tion in the joist space, the ceiling material, the type of roofing and color.
Figure A12-16 (ahead two pages) summarizes the base
case CLTD values for this type of construction. These values represent the average ceiling load condition that occurs during the afternoon. They are used to estimate ceiling loads for all Manual J applications.