General Goals and Approach

 

For more than three decades, I have overseen an energy-efficiency program at the University of California, Irvine -- an integral part of the University of California’s commitment to develop scalable, durable climate solutions.  The first principle of environmental sustainability is “use less.”  UC Irvine has developed efficiency practices, innovations, and standards for both new buildings and retrofitted older buildings that, in the aggregate, have reduced energy consumption (per square foot per year) by 50 percent.  Therefore, I set the goal at 50 percent improvement for my unit at 968 Fairway Circle.
 

For most structures -- including commercial, institutional, and residential buildings – windows are the weak link in terms of thermal energy loss.  Large windows, even though they are fixed (not operable) and sealed double-pane glass, conduct approximately seven times as much heat (from indoors to outdoors in the winter, vice-versa in the summer) as do the insulated exterior walls in Snowcreek 5.  So, this was the first priority to improve overall energy performance.  Reducing air infiltration was not initially a priority, but I discovered that many windows leaked air especially at the top at of the interior trim casing (more on this below).  Also, almost every outlet and switch in both the exterior walls and, surprisingly, in the common wall (the wall between units) leaked noticeable air infiltration, especially on windy days.
 

Insulating the underside of the lower floor (the upper side of the crawlspace) was done because, even though the perimeter of the crawlspace is insulated, the lower floor was markedly cooler than the upper level due to heat convection via the open stairway, and the floor was uncomfortably cool underfoot (wearing stockings) in the winter.  Moreover, the lower floor surface does constitute a rather large uninsulated area yet the cost to insulate it was reasonable.  Under-floor insulation has made the lower level more comfortable and reduced the temperature differential between the first and second floors.  The downstairs floor is now comfortable to walk upon wearing socks on a typical winter day (e.g., 20 degrees overnight, 35 degrees daytime high).

I have outlined below in detail the measures summarized above, as well as a number of smaller yet significant energy retrofit measures.  

 

Details

 

Windows

 

1. Experimentally evaluated four types of cellular shades:  single-layer cellular, double-layer (also called double-cell) cellular, “blackout” cellular with heat-reflective foil lining the interior of the outer layer of cells, and “blackout” cellular with side-rails to create a perimeter seal.  Double-cell “blackout” cellular shades with reflective surface inside the exterior layer of cells were selected since measurements revealed that they are almost as thermally efficient as the same type shades with the side-rails, while the latter added cost and occasionally the side-rail channels would jamb.
    

2. Installed “blackout” double-shell cellular shades (third type mentioned above) on sliding door and all fixed-glass windows except the ones above the slider and the main entry.  Installed motorized controls for the shades on larger windows.
    

3. Installed fixed interior low-e (low thermal emissivity) storm windows on all large fixed-pane (non-operable) windows.  Interior storm windows provide several advantages: 
   (A) They enable a wider air-space between the storm window and the fixed double-pane glass than attainable with exterior storm windows. 
   (B) Exterior storm windows require mullions for the larger windows (which would change exterior appearance), whereas interior storm windows did not require mullions. 
   (C)  Interior storm windows are generally easier to install than exterior storm windows. 
   (D) Interior storm windows’ perimeter seals (weather-stripping) provide excellent air infiltration performance. 
    

4. Smaller fixed-pane windows had low-e exterior storm windows installed.
    

5. The combined effect of installing the cellular shades plus the storm windows described above reduced heat loss through these windows by about two-thirds.  This seemed remarkable since original fixed-glass windows were already high-quality double-pane units, however the interior and exterior storm windows installed are “low-e” (low thermal emissivity) glass, and the deep window jambs (due to the 2x6 inch exterior wall framing) enabled the installation of both storm windows and double-cell thermal shades creating a total of five insulating airspaces.  These multiple airspace layers have an additive effect, providing excellent total insulation.
    

6. Installed thermal curtain liners for operable bedroom (casement) windows and bedroom slider.  (Discovered that, despite some advertising claims, the thicker, felt-like thermal liners insulate best.) And the best curtain rods for thermal curtain liners have two, parallel curtain rods separated by about two inches, and curved 90 degrees at the outer ends to return to the wall.  I affixed the side edges of the thermal liners to the edges of the window casing (trim) using upholstery tacks to stop heat convection (i.e., drafts) at the outer edges of the thermal liners.  These tacks and the thermal liners are not visible because they are behind the primary curtain seen from inside the room.
    

7. For the crank-operated transom windows (the ones that extend outward at the bottom when opened, below the large fixed-glass windows) I ordered Plexiglass panels the exact size and thickness of the removable screens.  These clear panels simply drop into the window screen recesses during the winter.  (I did notice slight condensation on the Plexiglass panels on cold days, but not enough to cause condensate weeping.)
    

8. Interior and exterior storm windows mentioned above are weather-stripped along perimeters (except at the bottom for exterior storm windows, per installation instructions).
    

9. Note that in order to install my interior storm windows I built temporary scaffolding in my unit for the high windows’ storm windows.  Most people will prefer to have these professionally installed.  Require installer to carefully observe installation cleaning requirements for low-e windows, which require a specific cleaning method to avoid scratching the low-e coating.

 

Air infiltration

 

1. Many windows had surprising air infiltration that was discovered by simultaneously turning on all five exhaust fans in my unit with all windows and exterior doors closed, which provided enough total suction to feel noticeable points of infiltration on a cold day.  Many of the windows had a gap at the top casing (trim) that was not visible except from a ladder.  These were filled with caulking if small, or expanding foam sealant if large.  (Local DIY store has a remarkable assortment of caulking sealants and expanding foam sealants.)|
    

2. Also, sealed air infiltration leakage at wall outlets and switches – both in the exterior walls and in the wall shared with the neighboring unit.   Caulked or used expanding foam sealant around all switch boxes and outlet electrical boxes. (For a margin of safety, I recommend turning off the electricity at the circuit breaker panel for electrical boxes while sealing them.)
    

3. Also installed foam sealant pads under switch plates and outlet plates on exterior walls, ensuring that these sealant pads were wide enough to cover the entire electrical box cutout gap.
    

4. Adjusted front door hardware so that weather-stripping makes contact along its entire length (check using a thin note card-size piece of thin plastic)
    

5. Checked seal at bottom of front door for contact across entire threshold.
    

• Installed thin, closed-cell adhesive weather-strip on front door jamb on the hinge side, which compresses forming an extra seal along this edge when the door is closed.

• Checked condition of weather-stripping on sliders.

• Window casing trim along the sides and bottoms of windows was caulked if there was any visible crack, in addition to the tops of windows that were mostly in need of sealing, as noted above.

 

Lighting

 

1. Replaced all fixture lighting, fluorescent lighting, and plug-in lamps with 2700K LED lamps.  Note that 2700K (or 3000K at most) is the Kelvin temperature that does not disrupt human Circadian rhythms (causing sleep disorders for many people).
    

2. Installed motion-sensor switches for lighting that tends to be left on inadvertently, and moisture-sensing switches for bathroom exhaust fans.

 

Garage

 

1. Improved/adjusted garage-to-hallway door weather-stripping
    

2. Installed thin, closed-cell, adhesive foam tape strips (1/8 inch thickness, closed-cell adhesive weather-striping) that compresses between garage door sections when the door closes.
    

3. Adjusted garage door side-strips to minimize air and snow leakage into garage.  (It is easy to find air leakage points on a sunny day by closing the garage door and turning off the lights in the garage.)
    

4. Adjusted lower stop-limit on garage door closer and inspected rubber seal at bottom of garage door for complete contact when closed (also easy to check by closing the garage door during the day with lights off).
    

5. Installed foil-face bubble insulation on door leading from the garage into the lower hallway.
    

6. Installed the same foil-face bubble insulation on thin (1/16 inch) spacers (to create an airspace under the bubble insulation) covering inside of garage door.
    

7. Note that fire-rated insulation is required for exposed insulation in a garage.

 

• Insulated furnace ducts and water heater in furnace/laundry room

• Installed foil-face bubble insulation on water heater (same insulation as mentioned in D.5, above)

• Installed foil-backed fiberglass insulation on furnace ducts  (insulation / foil tape)

 

Crawl space insulation

 

1. Had professionally installed R-15 mineral wool insulation above crawl space between first floor joists.  (R-19 to R-30 batt insulation could fit between the floor joists but R-15 seemed sufficient based on temperatures in the crawl space which has insulated foundation walls.)
    

2. Insulation installers fixed insulation gaps on furnace ducts in crawl space

 

Miscellaneous

 

1. Checked aerators on all faucets
    

2. Installed diverters on furnace registers directly under windows so that the hot air is aimed into the room rather than trapped behind the curtains
    

3. Replaced most appliances with Energy Star units
    

4. Installed low-speed (low wattage) fans for air circulation and summer comfort in several rooms
    

5. Sealed leaks at the transition from furnace distribution ducts to heat registers.  (These were leaking heat into the crawl space or into floor framing.  This can be done from the top using a sealant that adheres to sheet metal; not necessary to fix these leaks from underneath.  I sealed these leaks using FlexGlue brand rubberized adhesive (from local DIY store).
    

6. Installed ENRG phase-change mats on upstairs surfaces that are air-exposed but not visible, such as the tops of kitchen cabinets, undersides of tables and furniture, etc.  These pads absorb heat at 73 degrees F. when the temperature is rising, and release heat at 73 degrees when the temperature is falling through the phase-change temperature.  (See:  https://phasechange.com/enrgblanket/)   Also increased run-time on furnace to equalize upstairs/downstairs temperatures.
    

7. Adjusted dampers for upstairs furnace ducts to reduce flow rate in order to get better temperature balance floor-to-floor.
    

8. Increased “run-time” of furnace fan (the amount of time the fan continues to run after the flame turns off) to help circulate warmer air from upstairs to downstairs rooms.  The on-line furnace manual explains where the micro-switch is in the furnace control box.  (Or you can have a technician change the run-time setting in 5 minutes.)
    

9. Excellent suppliers included High Country Lumber (notably Kim Miller, special order desk at High Country - Bishop); Larson Windows (ordered through High Country Lumber); and CellularWindowShades.com (direct-ordered).

 

Overall Energy Reduction Results
 

Evidence of improved efficiency was measured on a retrofit-specific basis – for example comparing heat loss through an insulated window (improved as described above) with the prior condition (double-pane glass with wood-slat blinds) using an infrared temperature sensor gun when outdoor temperatures were in the range of 20-25 degrees F., comparing before vs. after interior surface temperatures, which measures the rate of heat conduction from indoors to outdoors at the point of measurement.
 

Following fixed-window efficiency measures detailed above, the fixed-pane windows now conduct essentially the same amount of heat (per unit of area) as the insulated walls between the windows when the cellular thermal shades are down, as evidenced by a surface temperature differential of only 1-2 degrees F. between the surface of a closed cellular thermal shade and the adjacent wall surface (in a spot with no framing behind the sheetrock) when the outside temperature is in the 20s!  There is some heat convection around the edges of the thermal shades, but this appears to be minimal based on measurements.  In addition, sitting near one of these windows is more comfortable since radiant losses of body heat are not noticeable.
 

As a result of improved window energy efficiency and all the other measures outlined above, my consumption of utilities dropped fifty percent comparing 2020 with 2021 on a month-by-month basis, albeit with much higher occupancy in 2021 and sharply rising propane costs.  Adjusted for increased occupancy and inflation, I’m certain that energy consumption now reflects considerably more than a 50 percent improvement.

Although no summer energy savings (besides appliances and lighting) are realized from the efficiency measures outlined above, temperature control and comfort are noticeably improved.