This is San Francisco's heating and cooling page, built from San Francisco's own numbers: Census housing figures, the metro's ZIP codes and its NOAA climate record. TempReach USA routes your call to an independent local HVAC technician; the homework below is here so you know your home's likely problems before you ever make it.
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The median San Francisco home was built in 1967; 67.5% of the stock predates 1980, and the pattern this metro's own data ranks first is the refrigerant transition reaching older systems. TempReach USA is a referral service, not an HVAC company: one call connects you with an independent local HVAC technician serving your ZIP code.
Start with the raw material: 4,653,593 people, 1,866,271 housing units, and a housing stock whose middle home was built in 1967. That single date organises everything on this page. On one side of it stand the older districts — 40.6% of homes predate 1960, 67.5% predate 1980 — heated and cooled by systems renewed in pieces for decades, in homes across Alameda, Contra Costa, Marin, San Francisco, San Mateo. On the other side, the 14.0% built since 2000 run matched modern equipment, and fail in the newer ways. A San Francisco technician reads a home's build year the way a doctor reads a chart: it predicts, before a single panel is opened, which systems deserve suspicion first.
The pre-1980 stock is where most of the metro's HVAC character lives. Homes from those decades in Alameda County and across Alameda, Contra Costa, Marin, San Francisco, San Mateo were built with duct layouts from the first age of central systems, furnaces and condensers that have since been renewed piecemeal, and insulation standards from another era, and each of those choices is now at or beyond the age its makers expected of it. Owner-occupiers hold 55.4% of the metro's homes, so most of the people reading this page are reading about a system they own outright — one whose failures arrive as surprises only if nobody has looked at the pattern: cooling fading a little each summer, a furnace recovering a little more slowly, one room drifting a little further from the thermostat.
The growth side of the metro tells the opposite story in the same language. Oakland, Fremont and the subdivisions still filling in account for much of the 261,278 homes built since 2000 — matched systems, planned ductwork, heat pumps where the lots suit them. Their HVAC is not old; it is uniform, which creates its own calendar: everything installed in the same boom reaches each wear point in the same years, from the first condenser replacements to the first control-board failures, while 121 cooling degree days of annual heat keep demand on the system high.
Over everything sits the weather, and here it is measured rather than described: NOAA's station at SAN FRANCISCO DWTN, CA US averages 57.7 degrees across the year, with 3.3 days reaching 90 or more and 0.0 nights at freezing or below. A furnace feels that record as a season of relentless cycling; a condenser feels it as a summer without a quiet week; a heat pump feels both. The problem ranking below is what those numbers, crossed with the housing profile, produce for San Francisco specifically.
The metro's building eras on one side, its weather record on the other — and its heating and cooling where the two meet.
The distribution, in one breath: of every hundred San Francisco homes, 40.6 were standing before 1960, 26.9 went up in the two decades after, 18.4 in the two after that, and 14.0 have arrived since 2000. Percentages flatten the picture, so hold the counts beside them — 757,706 oldest-era homes, 261,278 newest — and the metro's heating and cooling stops being an abstraction: it is that many systems, of those ages, failing in that order.
This is, by the numbers, an old-system metro. The largest slice of its housing predates 1960, which means the typical serious job here involves equipment generations in their final chapters: ducts that leak by modern standards, furnaces renewed into them more than once, cooling added decades after the houses were built for heat alone. The newer bands exist — the growth since 2000 is real — but they are the supporting cast. San Francisco's HVAC identity was fixed by its earliest builders, and its problem list is written in their floor plans.
The second band in the table is the 1960-1979 stock: 502,027 homes, 26.9% of the metro. It is the transition generation — cooling arriving, heating generations overlapping, ducts mixed street by street — and it supplies San Francisco with its most diagnostic HVAC: two homes of the same year needing opposite answers, decided by what the builder happened to specify.
Start the climate half where the system starts: at the thermostat's two seasons. San Francisco's cooling answers 121 cooling degree days of load and its heating answers 2,781 heating degree days of cold at SAN FRANCISCO DWTN, CA US — an average temperature of 57.7 degrees that no individual week actually delivers. A heating and cooling system here is never in neutral; the record keeps it working at one end or the other all year.
Hold the two halves together and the rest of this page explains itself: the problems ranked highest here are the ones where San Francisco's dominant housing era and its climate record overlap. Change either dataset and the ranking changes — which is precisely why this profile is rebuilt from the records for every metro instead of carried over from the last one.
Listed in the order this metro's housing and climate data supports.
Refrigerant is never consumed, so a low charge in a San Francisco home means a leak to be found, not just a top-up to be sold; the repair addresses the cause or the symptom is already on its way back.
Air conditioning in San Francisco works against the local calendar: 121 cooling degree days a year at SAN FRANCISCO DWTN, CA US, with 3.3 days at 90 degrees or more. The failures follow that load — capacitors and contactors worn by relentless summer cycling, refrigerant charges drifting low on systems that have served a decade of heat, condensate drains clogging in the humid weeks. The older districts run the oldest condensers; the subdivisions around San Francisco run matched fleets installed in the same seasons, and both sides of the metro meet the repair call on the hottest week of the year. Locally the workload concentrates where the stock is oldest — the districts built around the 1960s first.
The local caseload behind this service is written in the climate figures: 121 cooling degree days a year and 3.3 days at 90 or above, pressing on a cooling fleet whose oldest members serve the 1,259,733 pre-1980 homes — in Oakland (438,072 residents) as much as in the oldest districts.
In San Francisco this service is booked most often through the problem patterns at the top of this page — the metro's housing data, not habit, sets the order. If your home is in the 67.5% built before 1980, mention its age on the call: it changes the parts the technician loads before heading to San Francisco and the rest of the metro.
A duct system remembers everything the house has done: the remodel, the shedding dog, the winter the filter went unchanged. Cleaning reads that memory out under vacuum pressure and leaves the airways themselves — not just the grilles — clean.
Duct cleaning in San Francisco is booked in waves that follow the housing: after the renovation seasons in the older districts, at move-in across the subdivisions, alongside system replacements everywhere. The work pairs naturally with the inspection that surrounds it — leaking joints found and sealed, a disconnected run in an attic discovered, insulation fallen where it should not be. The cleaning is the appointment; the findings are often the value. Count it in homes if you prefer: 1,259,733 built before 1980, 261,278 since 2000, one shared system of streets and seasons.
Count the systems and the diary fills itself: 1,735,054 households breathing through ductwork daily, the oldest of it in homes from the 1960s and the newest in the subdivisions past Hayward. What the cleaning finds follows the biography — dust in proportion to years, debris in proportion to renovations.
Where this service gets booked in San Francisco follows the map on this page: the older districts generate the deep-end work, the post-2000 subdivisions the wear-and-tear work, and the 343,394 homes in between split the difference. Telling the call center your home's build decade — most San Francisco owners know it within a few years — puts the right kit on the van the first time.
Maintenance is a partnership with a division of labor: the household changes filters and keeps the outdoor unit clear; the professional brings instruments, the checklist and the judgment to read what the measurements are saying.
Maintenance in San Francisco is a calendar with two appointments a year, written by the climate: one before the 3.3 hot days arrive, one before the 0.0 freezing nights do. The cooling visit works the outdoor unit — coils washed, refrigerant pressures read, capacitors and contactors tested, the condensate drain cleared before the humid weeks can clog it. The heating visit works the furnace or heat pump — burners and ignition, the exchanger's condition, venting, airflow. Between them they catch the failures this metro's systems rehearse every year, while those failures are still small. With a median build year of 1967, most of the metro's 1,866,271 housing units are working through the same ageing curve.
The maintenance caseload is the installed base itself: 1,866,271 housing units whose systems each face 3.3 hot days and 0.0 freezing nights a year. Around Berkeley (120,223 residents) as in the old core, the twice-yearly visit is what stands between that calendar and the emergency diary.
One local habit worth copying: San Francisco homeowners who mention their street's building era when they book get a better-matched visit, because a technician heading to a the 1960s home in Alameda County loads different parts than one heading to a new-build subdivision in Oakland. The service is the same; the preparation is local.
Three parts, one system: filtration captures what the air carries, humidity control keeps moisture where the building tolerates it, and ventilation replaces stale air on schedule. Equipment chosen for one part cannot do the others' work.
The air quality conversation in San Francisco starts with humidity more often than with gadgets. A home whose summer indoor humidity rides high grows musty at the coil and uncomfortable at the thermostat, and a home dried out by 2,781 heating degree days of winter runtime irritates skin, wood and sinuses in the opposite direction. The assessment measures before it prescribes: humidity in both seasons, the filter's actual condition and fit, the duct leakage that pulls attic or crawl-space air into the supply stream in the metro's older districts. The 22.89 inches of rain in an average year here is part of the story too — humidity loads every cooling coil in the metro.
Air quality demand in this metro is written by its sealed seasons: 3.3 hot days with the windows shut around the cooling, 0.0 freezing nights with them shut around the heat. The 261,278 post-2000 homes hold their air tightest; the older districts around Richmond exchange theirs with attics and crawl spaces.
Where this service gets booked in San Francisco follows the map on this page: the older districts generate the deep-end work, the post-2000 subdivisions the wear-and-tear work, and the 343,394 homes in between split the difference. Telling the call center your home's build decade — most San Francisco owners know it within a few years — puts the right kit on the van the first time.
A mini-split heats as completely as it cools; in San Francisco the cold-climate models' published low-temperature figures decide whether a room can retire its old heaters or keeps them as support.
Ductless work in San Francisco also follows the housing nobody else can easily serve: the historic core around San Francisco, where walls were never built for ducts, and the accessory dwellings and in-law spaces appearing across Alameda, Contra Costa, Marin, San Francisco, San Mateo. Each installation is a small design project — line-set routes, condensate paths, the outdoor unit's placement — fitted to a building that predates the very idea of central air. Done well, the result is the quietest heating and cooling in the house. The SAN FRANCISCO DWTN, CA US record — 2,781 heating degree days, 121 cooling — is the backdrop Alameda County technicians plan around.
The search territory for ductless is the metro's unducted stock: 757,706 pre-1960 homes built before central systems, plus the additions and conversions scattered through 1,735,054 households — in Daly City and the historic core alike, spaces the main system never reached.
One local habit worth copying: San Francisco homeowners who mention their street's building era when they book get a better-matched visit, because a technician heading to a the 1960s home in Alameda County loads different parts than one heading to a new-build subdivision in Oakland. The service is the same; the preparation is local.
From San Francisco to Hayward, San Francisco replacements routed through TempReach USA end in commissioning — measured charge and airflow — so the installed system matches the calculated one.
Across 179 ZIP codes, San Francisco heating stock reflects a median build year of 1967 — furnaces at every age, each diagnosed on its own sequence and condition rather than its birthday.
With 1,866,271 homes and a median build year of 1967, San Francisco heating stock spans every era of furnace and flue — each installation assessed on its own house, not on the outgoing unit's label.
Across 179 ZIP codes and housing from a median build year of 1967, San Francisco heat pumps are specified and serviced from heat-loss figures and low-temperature performance data, not nominal tonnage.
Across Alameda, Contra Costa, Marin, San Francisco, San Mateo, one climate fact shapes the configuration: 2,781 heating degree days against 121 cooling degree days tells whether the control's year is mostly a heating story, mostly a cooling story, or a genuine heat pump balancing act.
Across Alameda, Contra Costa, Marin, San Francisco, San Mateo, the local professional who answers knows the stock — a median build year of 1967 across 1,866,271 homes means systems of every age failing in their characteristic ways, from San Francisco to the metro's newest subdivisions.
San Francisco's commercial buildings span every era around a median build year of 1967 — and with the era goes the equipment, from aging single units over old storefronts to multi-zone systems in new developments, all serviced from a per-unit record.
Ask where this metro's HVAC diary fills up and the answer is a short story: The refrigerant transition reaching older systems first, leaky ducts losing air and energy close behind, and the services that answer them doing the bulk of the booked work. Everything else on the list above is the supporting cast — necessary, frequent enough, but not what San Francisco's housing stock, at its age and in its climate, principally demands. Read the service list as a weather report for the metro's systems and it stops looking like a catalogue.
Ranked for this metro alone, from its Census housing profile and NOAA climate record.
It is worth saying plainly what the transition is not. It is not a mandate to replace working equipment, not a deadline after which older systems become unusable, and not a verdict on the many R-22 and early R-410A systems still cooling San Francisco homes adequately. Systems are retired by economics and condition, not by calendar. What the transition changes is the slope of those economics: each year, the older generation's refrigerant and parts grow scarcer while the machine itself grows older, so the repair-versus-replace crossing arrives a little earlier than the same failure would have suggested a decade ago. Honest service practice in this metro states that slope openly and lets the household's own numbers — the unit's age, its condition, its history — make the call. The refrigerant in the pipes has become a fact of the house, like its roof's age: not urgent every day, and unwise to leave unexamined.
The mechanics underneath the policy are simple. A refrigerant is the working fluid of the cooling cycle: it evaporates indoors to absorb heat and condenses outdoors to release it, thousands of times a season. Each generation of fluid was engineered to improve on the last one's environmental profile and operating pressures, and each required its own hardware — compressors built for different pressures, oils that mix with one fluid and not another, metering set for one fluid's characteristics. That is why the generations cannot be swapped like brands of the same product, and why 'topping up' an older system always means its own fluid, sourced from whatever supply its generation still commands. In San Francisco, where systems from all three generations stand in neighboring yards, the diversity is a service reality: diagnosis begins with identification, because the same symptom — a system low on charge — carries three different expense structures depending on the nameplate.
Housing arithmetic shows the exposure: with 67.5% of San Francisco's homes built before 1980 and equipment replaced in long cycles ever since, a substantial share of the metro's systems belong to refrigerant generations the market has already succeeded. The nameplates say so, one address at a time.
Duct loss hides inside other complaints. It presents as an air conditioner that cannot keep up in July — because the supply run through the attic is delivering air that picked up heat the whole way there. It presents as dust that returns days after cleaning, drawn in through return leaks in the crawl space. It presents as a furnace that heats the basement ceiling handsomely and the bedrooms modestly. In San Francisco, where many homes route their ducts outside the conditioned envelope by design of their era, these presentations are common enough to have a standing place in a technician's first questions. Separating duct loss from equipment weakness takes measurement rather than opinion — pressures and temperatures at the registers compared with those at the unit — and the separation matters, because the remedies are entirely different and only one of them touches the actual loss.
The construction details explain the timeline. Duct joints are mechanical connections, and the sealants asked to make them permanent have finite lives: cloth-backed tape dries and releases, foil tape lifts at edges, and even mastic can crack where runs move with the building. Flex duct, common in the metro's later building decades, fails at its connections and where its inner liner is pierced or crushed — and a crushed section quietly throttles every room downstream of it. Meanwhile the spaces the ducts cross work against them: attic temperatures in a San Francisco summer turn an uninsulated or leaking run into a heat exchanger pointed the wrong way, and winter reverses the argument in the crawl space. A duct system is therefore not a fixed asset but a slowly changing one, and its delivered performance in any given year is an empirical question, not a memory of its installation day.
Climate sharpens the accounting: in San Francisco the supply runs cross attic air during 3.3 days a year at 90 degrees or more, and crawl-space cold through 0.0 freezing nights. A leak in those spaces is not a small percentage lost politely — it is conditioned air exchanged with the harshest air the house contains.
An ageing system rarely announces its age in one event. It negotiates. In San Francisco the negotiation sounds like a house that takes longer to cool on the same afternoon weather, a furnace that needs two cycles to do what one did, a blower audible through a vent that used to be silent. The equipment in the metro's the 1960s homes has usually been repaired in pieces across the years — a motor here, a board there — so its age is not a single number but a profile of generations bolted together. That profile is what a thorough maintenance visit actually reads: which components are original, which are renewed, and where the next failure is most likely to file from. Households that know their system's profile make calm decisions; households that meet it for the first time in a breakdown make hurried ones.
Judge an ageing system by its trend line, never by its kindest day. On its kindest day — mild weather, light load — almost any system in San Francisco can still argue for itself. The trend line is written elsewhere: in run times lengthening season over season, in the setting creeping to hold the same comfort, in the rooms that quietly dropped out of the system's reach. SAN FRANCISCO DWTN, CA US's climate record ensures the trend will be tested at both ends of the year — 3.3 hot days and 0.0 freezing nights in an average year. The households that read their trend early choose the terms of the ending, whether that ending is a renewed component, a planned replacement in a shoulder season, or a few more good years bought with honest maintenance. The households that wait for the system's verdict receive it in the weather least suited to hearing it.
The housing record is the evidence: 40.6% of San Francisco's homes predate 1960 and 67.5% predate 1980. Equipment lives and ages inside that stock, so the metro's systems are, as a population, exactly as old as its building history says they should be.
The oversized system is humidity's favorite accomplice. In San Francisco, cooling equipment has often been replaced like for like or rounded up in size over the years, and a unit with more capacity than the house needs satisfies the thermostat quickly — then stops, with the coil warming and its collected moisture still in the air stream's neighborhood. Temperature is a fast variable; moisture is a slow one. A house can hit its setting while barely denting its indoor humidity, and the gap between the two is where the clammy afternoons live. Correct sizing, correct airflow and longer, steadier cycles are the equipment side of the answer; the house side — ventilation of wet rooms, vapor sources managed, drainage and grade outside — decides how much burden arrives for the equipment to carry in the first place.
Working a humidity complaint follows the water. The first measurements are indoor: relative humidity readings in several rooms, at several times, since a single reading at the thermostat flatters the story. The second look is at the equipment's drying setup — system size against the home's actual load, airflow across the coil, cycle length on a typical afternoon, and the condensate drain's condition and output. The third look is at the sources: crawl space or basement moisture, bathroom and kitchen exhausts that vent into attics instead of outdoors, plumbing weeping quietly somewhere, grade and gutters delivering rainwater to the foundation. Only then does the remedy conversation make sense, because each layer has its own remedy — equipment setup, dedicated dehumidification, ventilation correction, source control — and prescribing from one layer for a problem living in another is how humidity complaints survive multiple service visits.
Count the load the way the coil experiences it: through the humid months, each pass of indoor air delivers moisture that must condense and drain before the air can feel finished. In San Francisco, where cooling degree days reach 121 a year, that invisible water work rivals the temperature work the system was named for.
Zoning is the structural answer built for exactly this geometry: dampers in the duct network, a thermostat for each zone, and a control that lets the single system answer different areas on different calls. The upstairs can hold its setting without freezing the downstairs; the addition can call without dragging the whole house with it. In San Francisco's larger homes — the multi-storey plans that multiplied in the the 1960s decades and after — zoning converts one compromised average into several kept settings. It is not the right answer everywhere: it needs ductwork that can be sectioned sensibly and a system whose sizing and controls suit the arrangement, which is why the assessment starts with the network's map. But where the map allows, zoning answers the complaint at its actual address — the mismatch between one measurement point and a houseful of different needs.
A technician approaching uneven temperatures starts by refusing the thermostat's version of events. The readings that matter are taken in the rooms: supply temperatures and volumes at the registers, room temperatures over a system's full run, the difference a closed door makes to a room whose return path runs under it. Then the network gets its walk — trunk sizes, run lengths, damper positions, the condition of the far sections — and the two datasets are laid together. Rooms starved by defects announce themselves against the map; rooms starved by design announce themselves against the plan, the orientation and the hour. Only at that point does the conversation turn to remedies, and it turns with the cause named: correction for defects, zoning for a sectionable network serving different loads, ductless capacity for the spaces that were never truly part of the original design. In Alameda County's housing, all three remedies are in daily use — the skill is in the sorting.
The solar arithmetic testifies daily: on the 3.3 days a year at 90 degrees or more recorded at SAN FRANCISCO DWTN, CA US, a roof-loaded second storey is a measurably hotter building than the floor below it, served by the same machine and judged by the same single thermostat. The divergence is not a malfunction; it is the design being outvoted by physics.
A mild climate is a kindness with a hidden clause: the weather rarely forces the issue, so systems in San Francisco can drift out of condition quietly, unexamined by extremes. The record at SAN FRANCISCO DWTN, CA US — 2,781 heating degree days against 121 cooling degree days — describes real work in both modes, but spread gently enough that a furnace can underperform for a whole winter without a crisis and an air conditioner can lose capacity across a summer that never quite exposes it. The season's discipline here is therefore self-imposed: an annual rhythm that does not wait for weather to schedule it. The heating proven once properly before the cool months, the cooling run under load before the warm ones, filters on a calendar rather than a symptom, and the coastal facts honored — outdoor units breathe salt-tinged air in many such metros, and coils and cabinets age by corrosion on a schedule the mild temperatures never announce. The payoff for the rhythm is longevity with honesty: equipment that lasts because it is looked at, and a household that learns its system's condition from a gauge in a calm month rather than from a failure in the one hot or cold week of the year, when this metro's systems all get examined at once.
The season loads San Francisco's systems the way its record at SAN FRANCISCO DWTN, CA US says it will: 2,781 heating degree days against 121 cooling degree days in an average year, against a housing stock whose median build year is 1967. The households that read the season early — filters, drains, a system run before the extreme weeks — are the ones whose calls stay schedulable.
In San Francisco the transition's map is the housing map, lagged by one equipment generation. The districts built around San Francisco and the the 1960s streets hold the metro's R-22 veterans, in homes that have already seen one full cycle of this story when the equipment before them was young. The middle suburbs hold the R-410A majority. The 261,278 homes built since 2000 carry early current-generation systems now reaching the age where their first major repairs will be quoted — into a market whose standard has already moved on again. Read as a whole, the metro's 1,866,271 housing units contain the refrigerant industry's last several decades standing in rows, and the service economy of the metro is, in part, the business of keeping all those decades running at once. The deep pattern for a homeowner is simple to state and slow to change: your system's generation is a property of your street's building era, and its implications were installed with the house.
Strip the pattern down to its inputs and the ranking stops being mysterious: 1,735,054 households depending on systems installed across a median build year of 1967, in a climate that swings between 3.3 days of serious heat and 0.0 freezing nights. Whatever pattern a metro with those inputs manufactures most, it manufactures here — the lead position is less a title than a consequence, recalculated from the same public records any sceptic can check.
The first visit follows a short, diagnostic list — each item ruling a branch of the problem in or out:
PROBLEM
SOLUTIONPopulation 836,321
Population 438,072
Population 228,518
Population 159,201
Population 124,260
Population 120,223
Population 115,759
Population 115,396
Population 103,555
Population 102,560
Population 88,531
Population 85,870
Also in the San Francisco metro: San Ramon (population 85,734), Redwood City (population 82,423).
Beyond San Francisco itself, the metro takes in Oakland (438,072 residents), Fremont (228,518) and the rest of the communities in the grid above — each fitted with heating and cooling in its own building era, which is why two streets in the same metro can need entirely different HVAC conversations. The ZIP list below is the full coverage footprint: if your code is on it, this page was written about your housing stock.
The map continues: Hayward (159,201), Concord (124,260), Berkeley (120,223), Antioch (115,759), Richmond (115,396). Different names, different decades — each community in Alameda, Contra Costa, Marin, San Francisco, San Mateo was fitted with heating and cooling in its own growth years, which is why two streets in the same metro can need entirely different HVAC conversations. The ZIP list below is the working definition of coverage; the housing behind each code is the working definition of the job.
Start with San Francisco itself: 836,321 residents, 18.0% of the metro — the centre the rest of the map orbits. Oakland (438,072) and Fremont (228,518) form the next ring out, housing with its own building decades and its own equipment generations. Beyond them the metro thins into the smaller communities in the grid above, each a few thousand households deep — small in population, identical in one respect: their systems answer to the same eras and the same weather as the big city's.
Draw the metro by its paperwork and it resolves into Alameda, Contra Costa, Marin, San Francisco, San Mateo — 5 jurisdictions sharing one housing stock and one weather system. Alameda County holds the historic centre and the densest share of the older homes; the surrounding counties hold the rings of growth around it. Permits and inspections follow those boundaries even though temperature never does, which is part of why the technician this page connects you to works these streets specifically.
Three neighbouring coverage areas begin where this one ends: Vallejo, CA, some 44 miles off; Santa Cruz, CA, 56 miles; and Santa Rosa, CA, 61 miles. Each keeps its own page because each keeps its own numbers — a different median build year, a different climate station, a different problem ranking. Boundary households should trust the ZIP list over the map: the code, not the compass, assigns the dataset.
Set San Francisco among its neighbours and the contrasts sharpen the profile: Vallejo, CA — metro population 455,376, median build year 1982 — sits 44 miles away; Santa Cruz, CA (258,852, median 1973) 56 miles; Santa Rosa, CA (486,444, median 1979) 61 miles. Three different housing stocks under three nearby skies, which is why each keeps its own page and its own problem ranking rather than borrowing this one.
The stock has a shape as well as a size. Owners hold 55.4% of it and renters 44.6%, a split that decides who notices a comfort problem first and who arranges the repair. The generations split 4.8-to-one in favour of the pre-1980 homes. And the map divides into 14 named communities across Alameda, Contra Costa, Marin, San Francisco, San Mateo, each carrying its era's share of the 1,866,271 housing units the Census counts here.
One line of San Francisco arithmetic — a median home 59 years old · 961,220 owner-occupied homes against 773,834 renter-occupied · 4,233 pre-1960 homes for every covered ZIP code · a heating-to-cooling degree-day ratio of 22.91 · 581 mm of rain in an average year.
County pages carry the local detail — land area, climate normals and the heating and cooling pressures on the ground in each county.
More plain-language help: the TempReach USA heating & cooling guides
Describe the problem and the call center routes you to an independent local HVAC technician who works in the San Francisco metro.
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