520 N Christopher Columbus Blvd

Where 520 N Christopher Columbus Blvd is

Its block in Center City Philadelphia, drawn from Philadelphia's own building outlines and street centerlines.

The plan: window line, shape and floor rhythm

35 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.

The typical floor has 656 ft of exterior wall, and across 7 residential floors the building carries 4,589 ft of it in total, divided among the 131 homes this screen estimates.

Its plate is compact at 0.75: close to a square or a circle, the most efficient envelope an office can have and the least generous one for apartments: little perimeter to divide among homes. How window line and plate shape are measured.

At the model’s 750 sq ft average, the plan works out at about 18.7 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.

Why 520 N Christopher Columbus Blvd scores 42 out of 100

Daylight efficiency 57, Interior depth 2, Scale 87, Finance 20 — each out of 100, then weighted.

Most of what it earns comes from daylight efficiency, and what holds it back most is interior depth, at 2 out of 100: deepest interior point 79 ft from a facade, scored from 80 ft down to 40 ft.

Built in 1895

Philadelphia records this building as going up in 1895, which puts it in the pre-1920 stock.

As a rule, the era that converts most readily: load-bearing masonry, small floor plates laid out before deep-plan offices were possible, operable windows and generous floor-to-floor heights. The usual obstacles are not daylight but hazardous materials, lifts and bringing structure up to current code. That is the era’s general tendency rather than a finding about this building — the model reads an outline and a height, and can see nothing inside — but it is the first thing an architect would want to know, and it colours how much confidence the 69% daylight figure above deserves.

What the conversion would cost

$360 per square foot all-in across 179,218 sq ft of converted floor, or $64.5M in total — about $493K for each of the 131 homes.

That cost is charged across every converted square foot, including the 56,405 sq ft of windowless core, which has to be gutted, re-plumbed and sprinklered like the rest of the building and then earns nothing. Against it the model sets a completed value of $197K a home, which for 131 homes is $25.8M.

What would have to be true

A $38.8M gap before any grant, $30.9M after the modeled one. The smallest single change that would close it: average unit size 53% down.

The shortfall before any grant is $38.8M. Closing it from the value side means each of the 131 homes finishing at $493K rather than the $197K the model assumes — 150% more. Closing it from the cost side means getting all-in cost down from $360 to $144 per square foot.

A modeled RESIDE grant of $7.9M moves that threshold to $433K a home. That is still above the $197K assumed, leaving $30.9M uncovered, which is why the grant does not unlock this one.

Nor do all four levers have to move. For 520 N Christopher Columbus Blvd, one alone would close the gap at:

All four are sliders in the survey, where 520 N Christopher Columbus Blvd re-scores against your own numbers.

How it compares in Center City Philadelphia

520 N Christopher Columbus Blvd ranks 74th of the 103 buildings screened here, against a median score of 67.

Its floor plate is better lit than 34% of them, and shallower than 21% of them at its deepest interior point. On size it is the 63rd largest by estimated homes. The full survey of all 103 buildings ranks and maps every one of them, and the list by address links each to its own page.

Within the CMX4 zone

11th of 15 zoned CMX4 — the comparison that shares its rules, rents and streets.

15 of the screened buildings are zoned CMX4. 520 N Christopher Columbus Blvd ranks 11th of them against a median score of 58. 5 score 70 or more, their median deepest interior point is 64 ft from a facade against this building’s 79 ft, and together they would hold an estimated 4,016 homes. The group’s top scorer is 901 Arch St, at 84.

Its nearest match in size: 309 Callowhill St

The screened building closest to 520 N Christopher Columbus Blvd in converted floor area is 309 Callowhill St: 182,203 sq ft over 6 stories, against 179,218 sq ft over 8 here.

520 N Christopher Columbus Blvd scores 42 to its 62, and with the size held roughly equal most of that shortfall comes from interior depth: 2 out of 100 here, 43 there (deepest interior point 63 ft from a facade, scored from 80 ft down to 40 ft). On the money they sit in the same place: each falls short even with the modeled grant. The two stand about 2,100 ft apart.

Would it qualify for a RESIDE Act grant?

The model awards 520 N Christopher Columbus Blvd $7.9M, 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.

It does not sit in a 2018 designated Opportunity Zone, so it would not draw that Section 201 priority.

Other buildings screened near 520 N Christopher Columbus Blvd

The 4 closest the screen also covers, from 1,600 ft away. They are the colored outlines on the plan at the top of this page.

• 461 N 3rd St
  5 stories · 100% daylit · 53 estimated homes · scores 84/100 (Strong candidate)
  about 1,600 ft away
• 829 N American St
  3 stories · 81% daylit · 37 estimated homes · scores 60/100 (Worth a feasibility study)
  about 1,840 ft away
• 309 Callowhill St
  6 stories · 76% daylit · 146 estimated homes · scores 62/100 (Worth a feasibility study)
  about 2,100 ft away
• 441 N 5th St
  4 stories · 73% daylit · 48 estimated homes · scores 46/100 (Marginal)
  about 2,470 ft away