80 S Market St
80 S Market St is a 10-story building in Downtown San Jose with 96% of its floor area within daylight reach of a facade. This screen estimates 243 homes and scores it 94 out of 100 for office-to-residential conversion suitability.
CA-18 · Screened 2026-09-12 · Strong candidate
Also addressed as 90 S Market St and 55 W San Fernando St: San Jose’s address records place all 3 on this one footprint.
Where 80 S Market St is
Its block in Downtown San Jose, drawn from San Jose's own building outlines and street centerlines.
- Already housing
- Not screened
- 80 S Market St
This building's conversion pencils at default assumptions without any subsidy.
Every floor carries 1,050 sq ft of windowless core — area that must be gutted, seismically braced and sprinklered but can never be rented as an apartment. Across 9 residential floors that is 9,448 sq ft of cost carrying no revenue.
Modeled conversion metrics for 80 S Market St, 2026-09-12.
| Suitability scoreStrong candidate | 94 / 100 |
|---|---|
| Storiesfrom 116 ft LiDAR height ÷ 12 ft floor-to-floor | 10 |
| Floor plateper floor, from the city footprint | 26,403 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 96% |
| Deepest interior pointviability threshold is 80 ft | 49 ft |
| Windowless coreper floor — renovated but never rentable | 1,050 sq ft |
| Estimated homesat 750 sq ft average | 243 |
| Conversion cost$405/sq ft all-in on 237,626 sq ft | $96.2M |
| Gap before grantpencils unsubsidized | -$7.0M |
| Modeled RESIDE grantat the statutory per-award cap | $10.0M |
| BuiltSan Jose does not publish a construction year with this data | — |
| ZoningDowntown San Jose | DC |
| Opportunity Zonecensus tract 06085500800, 2018 designation | Yes |
The plan: window line, shape and floor rhythm
40 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 1,090 ft of exterior wall, and across 9 residential floors the building carries 9,811 ft of it in total, divided among the 243 homes this screen estimates.
Its plate is elongated at 0.28: a slab or an L, which is why so much of the floor lies within reach of a window: the outline buys daylight that a square plan of the same area would not. How window line and plate shape are measured.
At the model’s 750 sq ft average, the plan works out at about 27.0 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 80 S Market St scores 94 out of 100
Daylight efficiency 100, Interior depth 76, Scale 100, Finance 100 — each out of 100, then weighted.
Score components for 80 S Market St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency96% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 100 | 45% | 45.0 |
| Interior depthdeepest interior point 49 ft from a facade, scored from 80 ft down to 40 ft | 76 | 25% | 19.1 |
| Scale243 estimated homes, scored from 0 up to 150 | 100 | 15% | 15.0 |
| Financecompleted value covers conversion cost with 18% to spare, which tops out the component | 100 | 15% | 15.0 |
Most of what it earns comes from daylight efficiency, and what holds it back most is interior depth, at 76 out of 100: deepest interior point 49 ft from a facade, scored from 80 ft down to 40 ft.
What the conversion would cost
$405 per square foot all-in across 237,626 sq ft of converted floor, or $96.2M in total — about $396K for each of the 243 homes.
All-in cost per square foot for 80 S Market St: base cost plus the code work a change of use triggers.
| Base conversion cost | $260/sq ft |
|---|---|
| Seismic retrofit (change of use) | $45/sq ft |
| Plumbing risers to every unit | $40/sq ft |
| Operable windows and glazing | $30/sq ft |
| Additional egress stair | $18/sq ft |
| Fire sprinklers (NFPA 13R) | $12/sq ft |
| All-in | $405/sq ft |
That cost is charged across every converted square foot, including the 9,448 sq ft of windowless core, which has to be gutted, seismically braced and sprinklered like the rest of the building and then earns nothing. Against it the model sets a completed value of $425K a home, which for 243 homes is $103.3M.
What would have to be true
This one already clears the bar. The question is how much room it has before it stops.
At $425K a home, completed value covers the $96.2M of work with $7.0M to spare. Value per home would have to fall to $396K — 7% below the assumption — before the conversion stopped penciling, or all-in cost would have to rise from $405 to $435 per square foot. Neither is a wide margin in a market that moves, but this building does not need a grant to work.
Each of these, moved on its own, would be enough to undo that for 80 S Market St:
Single-assumption flip points for 80 S Market St, each holding the other three at their defaults.
| Completed value per homethe binding constraint — the least this building would need | 16% downto $355K |
|---|---|
| Circulation efficiency | 17% downto 67% |
| Average unit size | 20% upto 899 sq ft |
| Conversion cost per square foot | 28% upto $332/sq ft |
All four are sliders in the survey, where 80 S Market St re-scores against your own numbers.
How it compares in Downtown San Jose
80 S Market St ranks 9th of the 82 buildings screened here, against a median score of 64.
Its floor plate is better lit than 91% of them, and shallower than 82% of them at its deepest interior point. On size it is the 31st largest by estimated homes. The full survey of all 82 buildings ranks and maps every one of them, and the list by address links each to its own page.
Within the DC zone
7th of 72 zoned DC — the comparison that shares its rules, rents and streets.
72 of the screened buildings are zoned DC. 80 S Market St ranks 7th of them against a median score of 61. 31 score 70 or more, their median deepest interior point is 68 ft from a facade against this building’s 49 ft, and together they would hold an estimated 23,276 homes. The group’s top scorer is 1 Almaden Blvd, at 100.
Its nearest match in size: 210 S 1st St
The screened building closest to 80 S Market St in converted floor area is 210 S 1st St: 249,451 sq ft over 7 stories, against 237,626 sq ft over 10 here.
80 S Market St scores 94 to its 50, and with the size held roughly equal most of that lead comes from daylight efficiency: 100 out of 100 here, 45 there (62% of the floor area within 35 ft of a facade, scored from 40% up to 90%). On the money they part ways: 210 S 1st St falls short even with the modeled grant, while 80 S Market St pencils without a subsidy. The two stand about 1,000 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 80 S Market St $10.0M, on the assumption it qualifies. Whether it does, no published dataset can say.
That figure assumes the building meets the Act’s vacant-and-abandoned test, which turns on code-enforcement and receivership records no city publishes.
This building does sit in census tract 06085500800, a 2018 designated Opportunity Zone, which Section 201 lets HUD favor — one of the few statutory priorities this screen can actually check.
Other buildings screened near 80 S Market St
The 4 closest the screen also covers, from 180 ft away. They are the colored outlines on the plan at the top of this page.
- 60 S Market St18 stories · 79% daylit · 241 estimated homes · scores 78/100 (Strong candidate)about 180 ft away
- 104 S Market St8 stories · 86% daylit · 164 estimated homes · scores 87/100 (Strong candidate)about 230 ft away
- 30 Post St17 stories · 63% daylit · 438 estimated homes · scores 51/100 (Worth a feasibility study)about 250 ft away
- 95 S Market St8 stories · 59% daylit · 163 estimated homes · scores 35/100 (Marginal)about 290 ft away
A screen, not a feasibility study, from outlines and heights rather than plans: the method and how to correct a figure. If you know this building’s interior, you know what this model cannot see.