maintainable.xyz/house-spec
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
main
house-spec/specs/06-datacenter-spec.md

25 KiB
Raw Permalink Blame History

Home Datacenter Specification — Cellar, Racks, Cooling, Elevator

1. Design Philosophy

Self-hosted infrastructure. No cloud dependency for critical services. Full data sovereignty, minimal latency, maximum control.

  • Cellar location: Thermal mass of underground concrete stabilizes temperature year-round. Sound isolation protects the living space above. Physical separation from living areas provides security and fire containment.
  • Closed-loop cooling: Datacenter air never mixes with the house air system. The cellar is a separate fire compartment with its own climate control. No impact on the H13 HEPA-filtered living space air quality.
  • Heat recovery: In winter, the 10 kW of server waste heat exceeds the entire Passivhaus heating demand. Water-cooled rear-door heat exchangers can feed this heat into the Plafotherm ceiling heating loop — the datacenter heats the house for free.
  • Goods elevator: Server racks, UPS batteries, and cooling equipment are heavy. A dedicated goods lift connects the ground floor to the cellar, making equipment installation and maintenance practical.
  • Same maintainability principles: Modular racks, hot-swap components, accessible cable management, full environmental monitoring via Home Assistant.

The datacenter is not an afterthought. It is a purpose-built, climate-controlled, fire-separated facility with redundant power, cooling, and connectivity.

2. Cellar Structure

The cellar is reinforced concrete construction — Baufritz timber-frame is for above-ground only. The cellar is built first, and the Baufritz house is erected on top of the cellar slab.

2.1 Dimensions

Area Minimum Size Purpose
Datacenter room 20-25 m2 4 racks + cooling units + hot/cold aisle space
Electrical distribution room 6-8 m2 Main distribution board, cellar sub-board, UPS
Elevator machine room 4-6 m2 Hydraulic pump unit (if hydraulic drive)
Utility / storage 10-15 m2 General storage, future expansion
Total cellar footprint 40-55 m2
Parameter Requirement
Ceiling height >= 2800 mm clear (42U rack = ~2000 mm + cable trays + cooling overhead)
Floor-to-ceiling structural >= 3000 mm (allows for cable tray + lighting below ceiling)
Door width (datacenter) >= 1200 mm (rack on trolley clearance)
Door type T30 fire-rated, self-closing, smoke-tight

2.2 Construction Requirements

Requirement Specification
Construction Reinforced concrete (C25/30 minimum)
Waterproofing White tank (Weisse Wanne) per DIN 18533, or external bituminous membrane
Radon protection Continuous with house radon membrane — sealed at cellar/ground floor junction
Floor finish Power-floated concrete with epoxy anti-dust coating
Wall insulation Internal insulation (XPS or mineral wool) to prevent condensation, avoid thermal bridge to living space
Fire rating F90 ceiling/walls separating cellar from ground floor (DIN 4102 / EN 13501)
Ventilation Dedicated mechanical exhaust (UPS battery off-gassing), separate from house MVHR

2.3 Floor Load Capacity

Load Case Value Notes
Loaded 42U rack 800-1000 kg Concentrated on 4 feet, ~600x1000 mm footprint
Point load per rack foot ~2.5 kN Must not exceed concrete slab capacity
UPS with batteries 300-500 kg Concentrated load
Distributed live load >= 5.0 kN/m2 Per DIN EN 1991-1-1 (storage/industrial category)

Reinforced concrete slab handles these loads easily. No raised floor required in the cellar — cables route overhead in ceiling-mounted trays.

3. Rack Layout

3.1 Configuration

flowchart LR
    subgraph COLD["Cold Aisle"]
        R1["Rack 1\nNetworking\n42U"]
        R2["Rack 2\nCompute\n42U"]
        R3["Rack 3\nCompute\n42U"]
        R4["Rack 4\nStorage\n42U"]
    end

    CU1["Cooling Unit 1\nIn-Row DX\n10 kW"] --> COLD
    CU2["Cooling Unit 2\nIn-Row DX\n10 kW\n(N+1 Redundancy)"] --> COLD

    COLD --> HOT["Hot Aisle\nContained\nCeiling Return"]

    style CU1 fill:#1a5e5e,color:#fff
    style CU2 fill:#1a5e5e,color:#fff
    style HOT fill:#8b0000,color:#fff
    style COLD fill:#1a3d5e,color:#fff

Layout: 4 racks in a single row, cold aisle facing the cooling units, hot aisle contained with ceiling return panels. The in-row cooling units sit at the ends of the row (or between racks 2 and 3 if center-mounted).

3.2 Rack Specifications

Parameter Specification
Type 42U server rack, 19-inch standard
Dimensions 600 mm wide x 1000-1200 mm deep x 2000 mm high
Recommended Rittal TS IT, Schneider NetShelter SX, or equivalent
Frame Welded steel, powder coated, RAL 7035 or RAL 9005
Static load capacity >= 1000 kg per rack
Cable entry Top and bottom, brush-strip sealed
PDU mounting Vertical, rear-mounted, 2x per rack (A+B feeds)
Side panels Removable, with key lock
Front/rear doors Perforated (>70% open area) for airflow
Grounding Each rack bonded to building equipotential bonding bar
Leveling Adjustable feet + floor anchor bolts

3.3 Rack Allocation

Rack Primary Function Power Budget
1 Networking: switches, router/firewall, patch panels, fiber termination 1-2 kW
2 Compute: servers, hypervisors 3-4 kW
3 Compute: servers, GPU, AI workloads 3-4 kW
4 Storage: NAS, backup, archival 1-2 kW

4. Electrical System

4.1 Total House Power Budget

Load Peak Power Notes
Datacenter IT 10 kW 4 racks, 2.5 kW average
Datacenter cooling 3-5 kW COP ~3 for precision cooling
Datacenter misc (lighting, monitoring) 0.5 kW
House MVHR + air system 1-2 kW EC motors, humidifier
House water system (pumps, UV) 0.5-1 kW Booster, distribution, recirculation
House heat pump 3-5 kW Heating/cooling for Plafotherm
House general (lighting, appliances, cooking) 5-8 kW Peak domestic load
Elevator 5-10 kW Intermittent, during operation only
Total peak ~25-35 kW

4.2 Main Distribution Board

Parameter Specification
Location Cellar electrical distribution room
Main fuse 3x80A (400V 3-phase) = ~55 kW capacity
Utility connection Coordinated with local Netzbetreiber (grid operator)
Metering Smart meter with Home Assistant integration
Sub-boards Ground floor, upper floor, technical room (air/water), cellar/datacenter
Surge protection Type 1+2 SPD at main board
RCD strategy Per-circuit RCDs (Type A for general, Type B for IT/UPS with DC components)

4.3 Datacenter Power Distribution

Parameter Specification
Sub-board location Cellar electrical room, adjacent to datacenter
Feed A 3-phase 400V / 32A from main distribution
Feed B 3-phase 400V / 32A from main distribution (independent path)
PDU per rack 2x vertical metered PDU (one per feed), 230V/16A per outlet
Outlet type IEC C13 / C19 (standard server power connectors)
Monitoring Per-outlet power metering, SNMP + Home Assistant
Circuit protection MCB + Type B RCD per circuit

4.4 UPS

Parameter Specification
Type Online double-conversion (VFI per IEC 62040-3)
Capacity 10-15 kVA (covers full IT load)
Battery runtime >= 15 minutes at full load (graceful shutdown)
Battery type Lithium-ion (longer life, less off-gassing) or VRLA (lower cost)
Location Cellar electrical room, ventilated
Monitoring SNMP + Home Assistant (battery health, load %, runtime remaining)
Bypass Maintenance bypass switch for UPS service without downtime
Transfer time 0 ms (online double-conversion, no transfer gap)

5. Cooling System

5.1 Requirements

Parameter Specification
Total heat rejection 10 kW IT load + internal gains
Closed-loop Datacenter air does NOT mix with house air
Inlet air target 18-27 C (ASHRAE Class A1)
Humidity target 20-80% RH non-condensing
Redundancy N+1 (2 units, each capable of full 10 kW)
Noise (indoor unit) < 55 dB(A) (below ground, isolated from living space)

5.2 Precision Cooling

Parameter Specification
Type In-row direct expansion (DX) precision cooling
Recommended Rittal LCP DX, Schneider InRow DX, or equivalent
Capacity per unit >= 10 kW sensible cooling
Quantity 2 (N+1 redundancy)
Refrigerant R32 or R410A
Indoor unit In-row, between or beside racks
Outdoor condenser Wall-mounted or ground-level, weather-protected
Condenser penetration Through cellar wall, sealed and insulated
Controls Modbus or SNMP, integrated with Home Assistant

5.3 Heat Recovery — Dual Mode

flowchart TD
    MODE{"Season?"} -->|Winter| WINTER["Heat Recovery Mode"]
    MODE -->|Summer| SUMMER["Heat Rejection Mode"]

    WINTER --> WC["Water-cooled rear-door\nheat exchangers on racks"]
    WC --> HP["Warm water 30-40C\nto Plafotherm ceiling loop"]
    HP --> HOUSE["House heated for free\nby 10 kW server waste heat"]

    SUMMER --> DX["DX precision cooling\nindoor units"]
    DX --> COND["Outdoor condenser\nheat rejected to outside"]

    style WINTER fill:#1a5e1a,color:#fff
    style SUMMER fill:#1a3d5e,color:#fff
    style HOUSE fill:#1a5e5e,color:#fff

Winter mode: The 10 kW datacenter heat load far exceeds the Passivhaus heating demand (~1.7-2.6 kW for 175 m2). Water-cooled rear-door heat exchangers capture server exhaust heat and feed warm water (30-40 C) into the Plafotherm ceiling heating circuit. The house heat pump can be largely or entirely bypassed in winter. Excess heat is still rejected outdoors.

Summer mode: Standard DX precision cooling. Indoor units cool the datacenter air, outdoor condensers reject heat. No connection to house heating loop.

Transition: Automatic changeover based on outdoor temperature and house heating demand, controlled via KNX/Home Assistant.

5.4 Airflow Management

  • Hot aisle containment: ceiling-mounted containment panels above the hot aisle, directing hot exhaust air to cooling unit returns
  • Blanking panels: all unused rack U spaces filled (prevents hot/cold air mixing)
  • Brush-strip seals: at all cable entry points (top and bottom of racks)
  • No recirculation: cold aisle air must pass through equipment, not around it
  • Aisle width: minimum 1200 mm cold aisle (front access), 900 mm hot aisle (rear access)

6. Network Infrastructure

6.1 External Connectivity

Parameter Specification
Fiber entry Minimum 2x independent fiber paths from street (ISP redundancy)
Fiber type Single-mode OS2 (future-proof for 100G+)
Demarcation Fiber patch panel in Rack 1 (networking rack)
ISP handoff LC/APC or SC/APC connectors
Entry route Underground conduit to cellar wall, sealed penetration

6.2 Structured Cabling

Segment Cable Type Quantity Notes
Cellar to each room Cat6a shielded 2x per room Dual-purpose: data + sensor (upgrade from sensor-only)
Cellar to ground floor 12-core OS2 fiber 1 bundle 10G+ backbone to ground floor
Cellar to upper floor 12-core OS2 fiber 1 bundle 10G+ backbone to upper floor
Within datacenter Cat6a shielded As needed Rack-to-rack, short patch
Backbone routing Via elevator shaft riser or dedicated cable riser Fire-stopped at each floor penetration
  • Cable trays: perforated galvanized steel, ceiling-mounted in cellar, 200-300 mm wide
  • Labeling: every cable labeled at both ends, per TIA-606 or equivalent
  • Testing: all Cat6a links tested and certified to Cat6a channel performance
  • Ground floor distribution: fiber terminates in a small wall-mounted enclosure, Cat6a distributes through Doppelboden floor cavity
  • Upper floor distribution: fiber terminates in upper floor enclosure, Cat6a through ceiling void or wall chases

6.3 Rack 1 — Networking

U Position Equipment
1-2U Fiber patch panel (ISP A + ISP B)
3-4U Router / firewall appliance
5-6U Core switch (10G SFP+ uplinks)
7-10U Cat6a patch panels (48-port, structured cabling termination)
11-12U Access switch(es)
13-14U KVM-over-IP
15-42U Reserved / expansion

7. Elevator / Goods Lift

7.1 Purpose

Transport server racks (300-800 kg loaded), UPS batteries, cooling equipment, and general heavy items between ground floor and cellar. Also provides accessibility and future-proofing.

7.2 Specifications

Parameter Specification
Type Goods lift / service elevator
Load capacity >= 1000 kg
Car internal dimensions >= 1100 mm wide x 1500 mm deep x 2200 mm high
Door width >= 1000 mm clear opening
Door type Single-panel sliding or bi-parting, automatic
Stops 2: cellar + ground floor (optional: upper floor)
Drive type Hydraulic (simpler for 2-stop, no machine room on roof)
Machine room Adjacent to shaft in cellar (hydraulic pump unit)
Power 400V 3-phase, dedicated circuit
Speed 0.3-0.6 m/s (goods lift standard)
Standards EN 81-20 / EN 81-50 (safety), DIN EN 13015 (maintenance)
Controls Simple call/floor buttons, interlock with fire alarm
Noise < 50 dB(A) at car (below ground, minimal impact)

7.3 Shaft Requirements

Parameter Specification
Shaft internal dimensions ~1600 mm x 2000 mm (car + counterweight + running clearances)
Construction Reinforced concrete, integrated with cellar structure
Pit depth ~1200 mm below cellar floor (hydraulic buffer / overtravel)
Headroom above ground floor Per EN 81-20 (depends on car height + travel + safety margin)
Fire rating F90 shaft walls (DIN 4102 / EN 13501)
Shaft door T30 fire-rated at each landing
Ventilation Natural or mechanical ventilation at shaft top

Baufritz coordination: The elevator shaft penetrates the ground floor slab and must be planned into the Baufritz structural design from day one. The shaft is reinforced concrete (part of the cellar structure), not timber-frame.

8. Fire Safety and Separation

8.1 Fire Compartment

Element Rating Standard
Cellar ceiling (floor of ground floor) F90 DIN 4102 / EN 13501
Cellar walls (if adjacent to other cellars) F90 DIN 4102 / EN 13501
Datacenter door T30, self-closing, smoke-tight DIN 4102
All penetrations (cables, pipes, conduit) Fire-stopped DIN 4102-9 / EN 1366
Elevator shaft walls F90 DIN 4102
Elevator shaft doors T30 at each landing DIN 4102

8.2 Fire Detection

System Specification
Primary Aspirating smoke detection (VESDA or equivalent) — very early warning
Alternative Optical smoke detectors, 1 per 20 m2, ceiling-mounted
Integration Connected to house fire alarm panel and Home Assistant
Action on alarm Alert to phone + audible alarm + optional: automatic gas suppression

8.3 Fire Suppression (Optional)

Parameter Specification
Agent Novec 1230 or FM-200 (server-safe, no water damage, no residue)
Design concentration Per agent manufacturer (typically 5-7% v/v for Novec 1230)
Room sealing All penetrations sealed to retain agent concentration
Pressure relief vent Required (prevents overpressure during discharge)
Hold time >= 10 minutes
If not installing gas suppression Rely on VESDA early detection + manual response + portable extinguishers (CO2)

8.4 Emergency Power Off (EPO)

  • Red mushroom-head EPO button at datacenter entrance
  • Cuts all IT power (both A and B feeds)
  • Does NOT cut cooling (prevents thermal runaway on stored UPS energy)
  • Does NOT cut lighting (safe evacuation)
  • Key-switch reset required to restore power (prevents accidental restart)

9. Environmental Monitoring

9.1 Sensors

Sensor Quantity Location Protocol
Temperature (inlet) 4 Front of each rack, mid-height Modbus / SNMP
Temperature (exhaust) 4 Rear of each rack, top Modbus / SNMP
Humidity 2 Cold aisle + hot aisle Modbus / SNMP
Water leak 4 Under each cooling unit + low points Capacitive / Zigbee
Smoke (VESDA) 1 system Ceiling-mounted sampling pipes Relay / Modbus
Power (per-PDU) 8 Each PDU (2 per rack) SNMP
Door contact 1 Datacenter entry door KNX / Zigbee
UPS status 1 UPS unit SNMP

9.2 Home Assistant Dashboard

Widget Data Source Purpose
Rack Temperature Map 8x temperature sensors Inlet/exhaust per rack, color-coded
Total IT Power PDU metering kW draw, trending
Per-Rack Power PDU metering kW per rack
Cooling Status Cooling unit Modbus Inlet/outlet temps, compressor status
UPS Status UPS SNMP Battery %, load %, runtime remaining
Leak Detection Water sensors Green/red map
Smoke Status VESDA Alert level (normal/pre-alarm/alarm)
Physical Access Door contact Open/closed, log
PUE (Power Usage Effectiveness) Total power / IT power Efficiency metric (target < 1.4)

9.3 Alerting

Condition Level Action
Inlet temp > 27 C Warning Push notification
Inlet temp > 32 C Critical Push + audible alarm
Inlet temp > 35 C Emergency Auto-shutdown non-essential servers
UPS on battery Warning Push notification, start graceful shutdown timer
UPS battery < 20% Critical Initiate graceful shutdown of all servers
Water leak detected Critical Push + audible alarm
Smoke pre-alarm Critical Push + audible alarm + prepare suppression
Smoke alarm Emergency Fire suppression discharge (if installed), EPO
PDU overload > 80% Warning Push notification
Door open > 5 min Warning Push notification

9.4 Remote Management

System Protocol Purpose
Server BMC / IPMI Dedicated VLAN, HTTPS Out-of-band management, remote console
KVM-over-IP Dedicated VLAN, HTTPS Emergency console access to any server
UPS SNMP v3 Battery monitoring, graceful shutdown trigger
Cooling units Modbus TCP or SNMP Temperature setpoints, status
PDUs SNMP v3 Per-outlet control, power cycling

10. Physical Security

Measure Specification
Datacenter door lock Electronic (badge or PIN code), access-logged
CCTV 1 camera covering rack aisle, NVR stored on local NAS
Cellar windows Security glazing (P4A per EN 356) or eliminated in datacenter room
Cellar external door Multi-point locking, security-rated
Rack locks Key locks on front and rear doors, unique keys per rack

11. Baufritz Coordination

11.1 Structural Integration

The cellar is a separate construction phase from the Baufritz house:

flowchart TD
    A["1. Excavation\nDig cellar footprint + elevator pit"] --> B
    B["2. Cellar Construction\nReinforced concrete walls, slab, waterproofing"] --> C
    C["3. Radon Membrane\nContinuous with house membrane above"] --> D
    D["4. Elevator Shaft\nConcrete shaft integrated with cellar"] --> E
    E["5. Cellar Slab Cured\nReady to receive Baufritz house"] --> F
    F["6. Baufritz House Erected\nTimber-frame on cellar slab"] --> G
    G["7. Elevator Installed\nCar, guide rails, hydraulic unit"] --> H
    H["8. Datacenter Fit-Out\nRacks, cooling, electrical, cabling"]

    style A fill:#4a4a00,color:#fff
    style B fill:#4a4a00,color:#fff
    style F fill:#1a3d5e,color:#fff
    style H fill:#1a5e5e,color:#fff

Critical coordination points:

  • Cellar slab top surface is the foundation for the Baufritz house — level tolerance, waterproofing, and radon membrane must be continuous
  • Elevator shaft penetrates the ground floor — Baufritz must design around the shaft opening
  • Electrical main distribution is in the cellar — risers must be planned into Baufritz wall/floor cavities
  • Fiber and Cat6a backbone risers from cellar to each floor — coordinate with Doppelboden cavity and ceiling void routing

11.2 Services Risers

Service Riser Route Notes
Electrical (sub-board feeds) Dedicated electrical riser From cellar main board to ground floor + upper floor sub-boards
Fiber backbone Cable riser or elevator shaft chase 12-core OS2 to each floor
Cat6a structured cabling Cable riser or elevator shaft chase Bundles to each floor, then Doppelboden/ceiling void
Heat recovery pipes (optional) Insulated pipe riser From cellar cooling loop to Plafotherm manifold in technical room

11.3 Construction Checkpoints

Phase Checkpoint
Excavation Pit dimensions verified, elevator pit depth confirmed
Cellar concrete Waterproofing complete, radon membrane sealed
Cellar concrete Elevator shaft walls cast, anchor bolt locations verified
Pre-Baufritz Cellar slab level tolerance verified (+/- 5 mm)
Pre-Baufritz Electrical conduits cast into cellar slab for riser penetrations
Baufritz erection Elevator shaft opening integrated into ground floor structure
Interior Elevator installed and tested
Interior Main distribution board installed, all sub-boards fed
Interior Cable trays installed in cellar
Interior Structured cabling pulled and tested
Interior Cooling system installed (indoor + outdoor + piping)
Interior Racks installed, grounded, PDUs connected
Completion UPS commissioned, battery test
Completion Cooling commissioned, temperature verification under load
Completion Fire detection commissioned, test alarm
Completion All sensors connected to Home Assistant

12. Datacenter Fit-Out Sequence

flowchart TD
    A["1. Electrical rough-in\nMain board, cellar sub-board, conduit"] --> B
    B["2. Cable trays\nCeiling-mounted, perforated steel"] --> C
    C["3. Structured cabling\nFiber + Cat6a backbone, patch panels"] --> D
    D["4. Cooling installation\nIndoor units + outdoor condenser + piping"] --> E
    E["5. Rack installation\nPosition, level, anchor, ground"] --> F
    F["6. PDU installation\nA+B feeds to each rack"] --> G
    G["7. Power-up test\nVerify all circuits, PDU metering"] --> H
    H["8. UPS installation\nBattery charge, transfer test"] --> I
    I["9. Network equipment\nSwitches, router, firewall, patch"] --> J
    J["10. Environmental sensors\nTemperature, humidity, leak, smoke"] --> K
    K["11. Cooling commissioning\nVerify temps under simulated load"] --> L
    L["12. Home Assistant integration\nAll sensors, alerts, dashboard"]

    style G fill:#1a5e1a,color:#fff
    style K fill:#1a5e1a,color:#fff
    style L fill:#1a5e5e,color:#fff

Key checkpoints (colored):

  • Step 7: Power-up test — verify all circuits, PDU metering reads correctly, UPS transfers without gap
  • Step 11: Cooling commissioning — run simulated heat load, verify inlet temperatures stay within ASHRAE A1 range
  • Step 12: Home Assistant — all monitoring live before production servers go in

13. Estimated Costs

13.1 Infrastructure (One-Time)

Item Estimated Cost Notes
Cellar construction (concrete, waterproofing) 40,000-70,000 EUR Depends on soil conditions, excavation depth
Elevator (goods lift, 2-stop, hydraulic) 25,000-45,000 EUR Including shaft finishing, installation
4x 42U racks 2,000-6,000 EUR Depending on brand
2x precision cooling units 8,000-15,000 EUR Including outdoor condensers
UPS (10-15 kVA) 3,000-8,000 EUR Including batteries
Main distribution board 3,000-6,000 EUR Including sub-boards
Structured cabling (fiber + Cat6a) 3,000-8,000 EUR Including testing and certification
Fire detection (VESDA) 2,000-5,000 EUR
Gas suppression (optional) 5,000-12,000 EUR Novec 1230 system
PDUs (8x metered) 2,000-4,000 EUR
Total infrastructure ~93,000-179,000 EUR Excluding servers and networking equipment

13.2 Annual Operating Costs

Item Annual Cost Notes
Electricity (10 kW IT + 4 kW cooling, 24/7) 8,000-12,000 EUR At 0.30 EUR/kWh
Elevator maintenance contract 1,500-3,000 EUR Annual inspection + service
Cooling maintenance 500-1,000 EUR Annual refrigerant check, filter clean
UPS battery replacement 500-1,500 EUR Every 3-5 years (amortized)
Internet (2x fiber ISP) 1,200-3,600 EUR Redundant connections
Total annual ~11,700-21,100 EUR
Reference in New Issue View Git Blame Copy Permalink