I live in a 160+ year old farmhouse. Electrical wiring upgrades have occurred as needed since the house was first fitted for electricity by my grandparents in the 1940s. When ownership passed to me in 2007, I couldn't even get insurance without upgrading the old fuse boxes (separate upstairs and downstairs apartments) to modern breaker boxes. I'd think they'd be more concerned about old wiring. Thankfully, it's all post-1940.
My MPOE (telco, cable Internet, and power) is in the southwest corner of the basement. The basement itself has a poured concrete floor, mostly reinforced walls (via concrete block) and both granite and old clay brick features. The "ceiling" is mostly less than 6' with fixtures that extend below that level. This is an old "working" basement rather than a finished one. There is a drain at the south wall and up to a half inch of water on the floor during a wet spring. This spring has been quite dry, thus no water on the floor.
High airflow computer power supplies hate humidity. I've stupidly burned through a couple discovering this. Low airflow and fanless systems seem to accumulate enough dry heat to survive. Since the basement is both my MPOE and an otherwise naturally cooled, out of the way space, this seems like the place to put servers and networking equipment. The humidity calls for a basement dehumidifier. Even without a server rack, the mold and deteriorating brick situation likely call for a dehumidifier. I can set humidity at a reasonable level and run collected water into my existing drain.
Whether your "server closet" is a basement, closet, attic or something else, consistent (lowish) temperatures and low humidity are a necessity. I'm somewhat jealous of my Northern California friends; even during the winter wet season, a section of an attached garage probably works just fine as long as heat can be exhausted upwards or out.
I have something of a fetish for rackmount equipment. For many, a simple 12U wall rack would work just fine. For serious geeks, nothing less than 42U will do. I'm somewhere in between, let's say 25U. I have an arch space under my chimney that is centrally located, not far my MPOE, and otherwise unused. We'll see whether I can use that or need to run exhaust heat to an exterior window. It might actually be easier to run exhaust heat up the chimney along with the furnace exhaust.
I started out thinking that my Asus RT-N66U might be capable enough to act as my main firewall/router. Now I'm thinking I need a more elaborate setup:
Cable Internet Gateway => External Firewall/Router => DMZ => Internal Firewall/Router
Equipment is not a problem; I have a ton of old, unused equipment perfectly suited for routing and filtering packets. Cases are a bit of a problem. I strongly prefer rackmount to a bunch of generic PC and consumer appliance cases. I want my rack to be beautiful; call it what it is: a pointless fetish. I demand satisfaction. ;-P
Rackmount cases are seriously expensive (quality 1U => $200 USD), presumably because they're specialized, enterprise equipment. I'm currently looking into repurposing some old 1U Cobalt RaQ3 cases to hold mini-ITX boards. Christian Vogel has kindly shared information about the front panel pinout of these cases on his blog. This is very cool, as I've been wanting to get into Arduino development and interfacing for a while anyway.
As always, feedback here or on G+ is welcome. Let's see some pictures of your setups. How are you managing environmental factors for your home equipment? What are your tips for those who are inclined to be your own networking and server gurus at home? As a side note, I've been gradually moving critical services to the AWS cloud, yet I still need decent networking, security, storage, media servers and playback, and home automation at home. I suspect others are in the same boat. Let's hear about it!