予防保全とは — What Is Preventive Maintenance?

Preventive maintenance (予防保全, yobō hozen) means performing scheduled inspections and servicing on equipment before failures occur, rather than waiting for a breakdown (事後保全, jigo hozen). For HVAC systems — which represent the largest share of energy consumption in most commercial buildings — a disciplined preventive maintenance programme delivers multiple benefits:

  • Extends equipment service life, deferring costly replacement
  • Maintains energy efficiency (dirty coils and clogged filters can increase energy consumption significantly)
  • Reduces the risk of sudden failures during peak summer or winter demand
  • Supports compliance with legal inspection obligations under the 建築物衛生管理基準

月次点検項目 — Monthly Inspection Tasks

These tasks should be performed every month during the operational season and can typically be completed by trained in-house facility staff.

  • ☐ エアフィルターの汚れ確認・清掃 — Inspect and clean air filters; replace if pressure drop exceeds manufacturer limits
  • ☐ 吹出口・吸込口の清掃 — Clean supply and return air grilles
  • ☐ ドレンパンの水溜まり確認 — Check condensate drain pan for standing water or algae growth; flush drain line
  • ☐ 異音・異臭の確認 — Listen for unusual vibration or noise from indoor and outdoor units
  • ☐ 設定温度と実測温度の差異確認 — Compare thermostat setpoint against measured room temperature to detect sensor drift
  • ☐ 冷媒漏れの目視確認 — Inspect refrigerant piping and connections for oil stains indicating refrigerant leaks

四半期点検項目 — Quarterly Inspection Tasks

These tasks require basic tools and slightly more technical knowledge. They are suitable for skilled facility technicians or an outsourced maintenance contractor.

  • ☐ 熱交換器コイルの清掃 — Clean evaporator and condenser coils using approved coil cleaner; check fin condition
  • ☐ ベルト駄損・テンション確認 — Inspect fan belts for wear and correct tension (belt-driven AHUs)
  • ☐ 軸受け潤滑 — Lubricate fan and pump bearings per manufacturer specification
  • ☐ 電気接続部の増締め確認 — Check and re-torque electrical terminal connections to prevent loose-contact heating
  • ☐ 冷媒圧力・過熱度の測定 — Measure suction and discharge pressures; calculate superheat and subcooling to verify refrigerant charge
  • ☐ 自動制御バルブの動作確認 — Verify operation of motorised control valves and actuators

年次点検項目 — Annual Inspection Tasks

Annual tasks are more comprehensive and typically require a licensed refrigeration engineer (冷凍機械責任者) or a qualified HVAC service technician.

  • ☐ 冷媒量の精密確認 — Precision refrigerant charge verification using manifold gauges and superheat/subcooling calculations
  • ☐ 圧縮機電流・絶縁抵抗測定 — Measure compressor running current and insulation resistance of motor windings
  • ☐ 全熱交換器エレメント洗浄・点検 — Clean and inspect total heat recovery exchanger elements
  • ☐ ダクトリーク検査 — Conduct ductwork leakage test on critical supply/return duct sections
  • ☐ 安全装置の作動試験 — Function-test all safety controls: high/low pressure switches, thermal overloads, freeze stats
  • ☐ 冷却塔の清掃・レジオネラ対策 — Clean and disinfect cooling tower basin; conduct Legionella risk management per 厚生労働省 guidelines
  • ☐ 冷凍機油のサンプリング分析 — Submit compressor oil samples for laboratory analysis to detect early signs of internal wear

記録管理の重要性 — The Importance of Maintenance Records

Every inspection and maintenance activity should be documented in a structured maintenance log (保守点検記録). Good records serve several purposes:

  1. Enable trend analysis — spotting gradual degradation before it becomes a failure
  2. Demonstrate compliance to regulators, insurers, and building owners
  3. Support equipment replacement decisions with objective performance history
  4. Transfer institutional knowledge when staff changes occur

Modern CMMS (Computerised Maintenance Management System) software makes scheduling, recording, and analysing maintenance activities far easier than paper-based systems. Several cloud-based platforms offer Japanese-language interfaces suited to domestic facility management operations.

保全コストの考え方 — Understanding Maintenance Costs

A common misconception is that reducing maintenance frequency saves money. In practice, deferred maintenance on HVAC equipment typically results in higher energy costs from reduced efficiency, more frequent emergency repairs (which cost significantly more than planned maintenance), and shortened equipment life requiring earlier capital replacement. Treating preventive maintenance as an investment — rather than a cost — is the key mindset shift for effective facility management.

まとめ

A well-structured preventive maintenance programme, carried out consistently and thoroughly documented, is the single most effective way to protect your HVAC investment. Use this checklist as a starting template and adjust frequencies based on your specific equipment types, operating hours, and environmental conditions.