172-180 Federal St

Where 172-180 Federal St is

Its block in Downtown Boston, drawn from Boston's own building outlines and street centerlines.

The plan: window line, shape and floor rhythm

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

The typical floor has 434 ft of exterior wall, and across 6 residential floors the building carries 2,605 ft of it in total, divided among the 63 homes this screen estimates.

Its plate is compact at 0.73: 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 10.5 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.

Why 172-180 Federal St scores 88 out of 100

Daylight efficiency 100, Interior depth 85, Scale 42, Finance 100 — each out of 100, then weighted.

Most of what it earns comes from daylight efficiency, and what holds it back most is scale, at 42 out of 100: 63 estimated homes, scored from 0 up to 150.

Built in 1899

Boston records this building as going up in 1899, 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 91% daylight figure above deserves.

What the conversion would cost

$360 per square foot all-in across 65,533 sq ft of converted floor, or $23.6M in total — about $374K for each of the 63 homes.

That cost is charged across every converted square foot, including the 5,716 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 $442K a home, which for 63 homes is $27.8M.

What would have to be true

This one already clears the bar. The question is how much room it has before it stops.

At $442K a home, completed value covers the $23.6M of work with $4.2M to spare. Value per home would have to fall to $374K — 15% below the assumption — before the conversion stopped penciling, or all-in cost would have to rise from $360 to $424 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 172-180 Federal St:

All four are sliders in the survey, where 172-180 Federal St re-scores against your own numbers.

How it compares in Downtown Boston

172-180 Federal St ranks 54th of the 96 buildings screened here, against a median score of 89.

Its floor plate is better lit than 56% of them, and shallower than 59% of them at its deepest interior point. On size it is the 81st largest by estimated homes. The full survey of all 96 buildings ranks and maps every one of them, and the list by address links each to its own page.

Within the SKY zone

27th of 52 zoned SKY — the comparison that shares its rules, rents and streets.

52 of the screened buildings are zoned SKY. 172-180 Federal St ranks 27th of them against a median score of 88. 40 score 70 or more, their median deepest interior point is 51 ft from a facade against this building’s 46 ft, and together they would hold an estimated 19,019 homes. The group’s top scorer is 147 Milk St, at 100.

Its nearest match in size: 62-74 Essex St

The screened building closest to 172-180 Federal St in converted floor area is 62-74 Essex St: 68,774 sq ft over 8 stories, against 65,533 sq ft over 7 here.

The two land within a few points of each other — 88 here, 90 there — so at this size the screen reads them as much the same prospect. On the money they sit in the same place: each pencils without a subsidy. The two stand about 1,400 ft apart.

Would it qualify for a RESIDE Act grant?

The model awards 172-180 Federal St $3.8M, 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 172-180 Federal St

The 4 closest the screen also covers, from 160 ft away. They are the colored outlines on the plan at the top of this page.

• 175 Federal St
  20 stories · 83% daylit · 232 estimated homes · scores 87/100 (Strong candidate)
  about 160 ft away
• 155 Federal St
  18 stories · 92% daylit · 191 estimated homes · scores 95/100 (Strong candidate)
  about 200 ft away
• 133 Federal St
  13 stories · 91% daylit · 117 estimated homes · scores 90/100 (Strong candidate)
  about 340 ft away
• 207-211 Congress St
  32 stories · 82% daylit · 550 estimated homes · scores 84/100 (Strong candidate)
  about 370 ft away