The Beadwall is a window insulation system invented by Dave Harrison of Zomeworks. Polystyrene beads are blown into the air cavity between two panes of glass when insulation is needed — at night or on overcast days — and sucked back out into storage drums when solar collection is wanted.
From Sunspots (1975, section 6.5):
The "beadwall" (patent applied for), invented by Dave Harrison, is an excellent method of preventing heat loss through a window. The first picture shows styrofoam beads being blown into the cavity between two clear glazings; the second shows them being sucked out. The power for emptying and filling is provided by an ordinary vacuum cleaner. The insulating value can be made whatever one wishes by increasing or decreasing the thickness of the space between the glass. The beads themselves are almost as effective per inch of thickness as the best commercial insulation.
Polystyrene beads are stored in drums adjacent to the window. A vacuum cleaner (or equivalent pneumatic source) blows them in through the top of the window cavity when insulation is needed; the same device sucks them out from the bottom when solar transmission is wanted. The insulation value is tunable: thicker bead layer = higher R-value. The beads approach the performance of the best commercial insulation per inch of thickness.
The system solves the fundamental window dilemma: windows are solar collectors by day and heat losers by night. The Beadwall makes the window's thermal properties switchable.
Baer documented three approaches to window insulation in the archive:
| System | Mechanism | Inventor | Complexity |
|---|---|---|---|
| Beadwall | Pneumatic beads between panes | Dave Harrison | Moderate — requires bead storage drums and vacuum pump |
| Nightwall | Rigid foam pressed against glass | Baer (1975) | Lowest — no moving parts, manual or canister-actuated |
| Skylid | Freon-actuated insulated louver beneath skylight | Baer/Boyd/Henry | Higher — refrigerant canisters, ball bearings, seals |
Baer's comment in Sunspots: "Such elegant inventions as the beadwall indicate that the healthy response of architecture to increasing energy costs may be increased use of glass in building walls rather than a retreat to underground buildings."
From the 2009 AIA passive solar slideshow: Frank's House / Beadwall — David Harrison, Designer, Placitas, NM (1980). The Monte Vista Beadwall Greenhouse is photographed in Sunspots (top: filling; bottom: emptying).
Dave Harrison (David Harrison) — VP of Zomeworks for 12+ years. The Beadwall is his invention, not Baer's. The same Harrison who later designed Frank's House in Placitas and who in 2004 told Baer's shareholders: "I've worked with this and Cool Cell technology for over 12 years and know it is reliable and really works."
The only long-term real-world performance data in the archive comes from a 1983 superinsulated home documented in a 2006 Fine Homebuilding forum thread:
| Parameter | Value |
|---|---|
| Airspace between panes | 4 inches |
| Bead storage | ~800 gallons in four 200-gallon outdoor tanks |
| Fill / empty time | ~5 minutes per window |
| Motors | Two per closet (one inflate, one extract) |
| 10-year maintenance cost | ~$200 (one motor rebuild) |
The home used a small wood stove as its only supplemental heat source. After 10 years of daily operation, the system required only one motor rebuild at approximately $200.
Humidity note: One forum commenter observed that higher humidity benefits the system — in arid Southwest climates, low humidity causes static electricity that makes dust cling to glass panes. This is the hardest environment for the Beadwall despite being Zomeworks' home market.
Baer on Harrison's invention (MEN, July 1973): "a problem that people have lived with for 80 or 100 years" — high praise from a man who rarely endorsed others' work.