By Thomas Soper AIA

Downtown view from the former Carnelian Room in the Bank of America Building

There are too many variables in architecture and urban planning to offer a “one size fits all” statement on re-purposing Office buildings downtown, but certainly, converting vacant downtown space is a watershed topic. Today, we have politicians and a public who want quick answers but have simplistic opinions on the subject and it becomes counter-productive to opine to convince politicians to do the right thing. It’s a little like how the YIMBY’s have succeeded (temporarily) with their simplistic views in convincing City hall to do the wrong things.

We have to ask the right questions. My advice is for the City to do the right thing which is to convert as much of the vacant office space downtown as soon as possible in a systematic and rational way, using the best practices of independent professions who know-how. That’s the bottom line because this crisis involves multiple emergencies, one of which we have never faced before and the sum total is an existential threat. That has to be the first and foremost objective to spearhead a consensus to address the pernicious urban decay that has taken hold downtown. Few want to be there. The exodus is real. The loss of tax base is real. The list goes on.

The reason I say pernicious is that I lived and first practiced in downtown Detroit during which it almost recovered in the mid 70’s. I witnessed first hand this scale of crisis. While the social causes of Detroit’s urban decay are different, Detroit’s coup de grace is becoming San Francisco’s fatal mistake: lack of leadership, factionalism, bureaucracy and absence of knowledge. We were forced to tear up our roots, endure the set-back and landed in SF.

On the brighter side, Gensler SF has done some recent investigations into converting office buildings into residential apartments. They would be a good local source for a more rational and hopefully a comprehensive perspective. It is also important to note that NYC is way ahead of SF in these proposals because it has both less factionalism and something call rent stabilization, not control. NYC is not a provincial town.

Let me illustrate why room height is off target for convincing others: I did two new office high rises in SF in the mid 80’s. For these two buildings the floor to floor height was 12′-6″. Take away 3 feet for structure and office HVAC leaves a ceiling of about 9’-6”. But this rule of thumb would be different if the building’s structural system was concrete. At the same time, I don’t view ceiling height as the most challenging in terms of conversion. But I caution you because there are many criteria that need to all be satisfied. Each building has to be quickly evaluated by a team of experts.

Ceiling heights are in general malleable in office buildings because apartment HVAC systems are smaller and are often put on the outside walls for fresh air make up. Back to minimum ceiling height, the code says that closets, kitchen and bathrooms can be as low as 7′-0″ and they don’t require natural light. This means these rooms must occupy space farther away from facades where natural light can enter.

I think that the BMR ceilings, other than closets, kitchens and bathrooms, in the “habitable” rooms are generally adequate up to 9′-0″ for residential use. But ceiling height is also a function of the plan dimensions of the room: the bigger the room, the higher the ceiling usually wants to be.

There are other more critical criteria that are more difficult to overcome:

1. Natural light and ventilation minimum requirements are written in the Code. There is a formula for minimum window sizes for all rooms other than closets, kitchens, and bathrooms.
2. Commercial building footprint typically occupy the entire parcel. Many office buildings are built right up to the interior lot lines facing other buildings with only one façade facing the street which must deliver all the natural light required by code.This is a worst case scenario but makes conversion into housing more challenging.
3. Structural column bay size and office building floor depth (horizontal) are deeper than apartment depth for natural light reasons. There are a number of ways that this can be mitigated, such as carving out large light wells but, that involves “orthopedic, pulmonary, and cosmetic surgery”.

So you are probably thinking, conversion might be too costly. Not necessarily so. The unit cost might be higher ($/sf) but less area is affected with conversion. The proper comparison is this: the total cost of conversion will likely be less than the total cost of whole scale demolition and stating all over again with new construction. (always compare “apples to apples”). When you think about it, renovation doesn’t require a new foundation, it doesn’t require too many new columns and maybe a new skin. Demolition is relatively less expensive by unit cost. These conversions would be a different paradigm, more like the medical analogy above.

Finally, why do this new kind of “surgery” on the office buildings to solve our multiple crisis today?

1. It’s not so new. Many Architects are well versed in these techniques. Politicians are not. Case in point: City Hall is base-isolated and I have never heard a politician mention it after the dedication ceremony.
2. It’s very likely cheaper to renovate when compared to tearing down and building back up.
3. These conversions can be designed to be reversible when the balance of office space comes back (or not)
4. We must shift rapidly to Type 4 construction where possible and design by code allowing for performance criteria and alternate means provisions. We have these skills readily available.
5. Here’s the big environmental argument. Concrete is by far the most deleterious material to Global warming. Steel is second. Renovation greatly minimizes this.

We might survive the BMR housing crisis by building with reckless abandon new units, but we will most certainly lose the existential crisis by using new construction. Renovation is the priority for all forms of construction for at least the next 10 years if not longer.

Thomas Soper AIA

Architect

P 1.415.902.9457

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RELATED:

PODCASTS / MULTIMEDIA

Bloomberg’s Odd Lots Podcast: What It Really Takes to Convert an Office Building Into Apartments

[7-6-23] // Joe Weisenthal & Tracy Alloway speak with Joey Chilelli, who has been involved with conversion projects for a decade. They discuss the challenges involved in actually pulling off these complex projects. (46 min.)

See also companion story.