Generator Gold: Slash Hotel Load Without Complaints

Simple Summary

Ease the thermostat a notch, slow fans when spaces are empty, and use ship heat (or a heat pump) before burning fuel to reheat air. Do this in small steps and log comfort. Most ships can cut HVAC power with almost no complaints if you change slowly and keep humidity and fresh air reasonable.

Quick wins (pilot on one deck)

• Setpoints: Raise cooling setpoint by +1 °C and lower heating by −1 °C. Apply night/berth setbacks in low-use areas.
• Ventilation: Switch constant-high fans to CO₂/occupancy control or timed schedules. Don’t over-ventilate empty spaces.
• Fans & pumps: Fit or enable VFDs on AHUs and loop pumps. Airflow ∝ speed; power roughly ∝ speed³—small slowdowns help.
• Reheat trap: Avoid cooling air only to reheat it. Balance coils/valves so you’re not fighting yourself.
• Heat source: Prefer waste-heat reclaim or a heat pump to pure electric reheaters where feasible.
• Maintain: Clean filters/strainers and coils; restore design ΔT on chilled/sea water loops.

HVAC Savings Estimator

Enter a realistic kW reduction from the pilot, your gen-cost per kWh, and hours per day affected.

Comfort guardrails (avoid complaints)

• Change setpoints in 0.5–1.0 °C steps; hold for 48 hours and log feedback.
• Keep humidity roughly 40–60% where practical; avoid cold drafts.
• Use CO₂/occupancy to cut airflow only in low-use zones; keep fresh air in busy/work spaces.
• Publish a simple “comfort promise” and a hotline/WhatsApp so crew can flag hot/cold spots quickly.

One-week rollout plan

1. Pick a pilot area (one deck / accommodation block). Note baseline kW from the power log.
2. Apply tweaks: setpoint shift, night/berth setbacks, CO₂/occupancy control, fan VFD slowdowns.
3. Log daily: HVAC kW, cabin temps, any complaints/resolutions.
4. Review after 7 days: keep what worked, roll back anything that didn’t, then expand to similar zones.

Example settings to test (tune to your ship)

• At sea (day): Cool 23–24 °C, fresh-air normal, fans 85–90% in occupied areas, 60–70% in low-use zones.
• At sea (night): Cool 24–25 °C, reduce airflow in corridors/stores, keep cabins reasonable.
• Alongside: Use setbacks in unoccupied spaces; consider shore power or waste-heat for reheat if available.

Simple Summary

Slow the motor, save the fuel. On pumps and fans, dropping speed a little cuts power a lot. Use VFDs and better control so flows match the real need, not “full blast, throttled by a valve.” Keep minimum flow and cooling limits in mind, and stage extra machines off instead of running two at half-speed when one at higher speed can cover safely.

Best targets (week-one hits)

• Seawater cooling pumps: Many run 100% with throttled valves. Add VFD, control by temperature or ΔT.
• Chilled-water pumps: Match flow to coil demand; fix stuck three-way valves first.
• Engine-room fans: Control by temperature/pressure; trim at night/berth where safe.
• Accommodation AHUs: Pair VFD with CO₂/occupancy logic so empty spaces aren’t over-ventilated.

Tip: If two pumps run at low load, try staging one off and letting the other handle demand (within limits).

VFD Savings Estimator (affinity law)

For fans/pumps: Power ≈ kW_base × (speed%)³. Small speed cuts → big kW cuts.

Estimator assumes safe operation above minimum flow/NPSH and within motor/VFD limits.

Control playbook (what to actually change)

1. Measure before you move: Log pump/fan amps and loop ΔT/pressure for 48 h.
2. Set a true control variable: e.g., chilled-water supply temp, ER pressure, CO₂ ppm.
3. Enable VFD control: Start with small trims (e.g., −5% speed), verify temps/pressures stay in band.
4. Stage off spares: If one machine at 70–85% can hold setpoint, stop the second.
5. Tune the PID: Eliminate hunting; widen deadbands so speed isn’t constantly chasing noise.

Common pitfalls (and fixes)

• Bypass loops defeat savings: Close unneeded bypasses; convert 3-way to 2-way where allowed.
• Running two at low instead of one at high: Stage off extras when safe to do so.
• Dirty coils/strainers: You’ll speed up to overcome fouling—clean first, then trim.
• Too slow → cavitation/min-flow breach: Respect pump minimum flow and NPSH; use a small recirc if required.
• Harmonics/EMC: Fit appropriate filters/chokes per class/vendor guidance.

Safety & class guardrails

• Keep within min. flow, NPSH, and motor cooling limits; confirm with maker’s curves.
• Maintain lube/cooling to critical equipment; don’t starve heat exchangers.
• Log settings changes and alarms; revert quickly if temperatures/pressures drift.
• Follow class/flag rules for VFD installations and EMC in machinery spaces.

One-week rollout (pilot)

1. Pick one seawater pump and one ER fan. Record baseline kW and temps/pressures.
2. Trim speed by 5–10% with alarms watched; verify ΔT/pressure are fine.
3. Try staging off a second unit if setpoints hold.
4. Enter results in the estimator and decide fleet rollout.

Simple Summary

Change old lights to LEDs and add simple controls so lights are bright only where people are, and dim or off everywhere else. LEDs use far less power and last longer. Sensors and timers stop empty rooms from burning fuel.

Best places to start (biggest wins)

• Corridors, stores, workshops: LED + occupancy sensors (auto off after 5–10 minutes).
• Accommodation & offices: LED panels + daylight dimming near windows.
• Decks & wet areas: IP66 LEDs with dusk/dawn timers.
• Engine room general lighting: phased swap to high-efficiency LED high-bays.

Keep safety lights and emergency escape routes fully compliant at all times.

LED + Automation Savings Estimator

Compare old vs new fixtures and add sensor savings. Uses your genset $/kWh.

Estimator ignores maintenance savings; real payback is often faster due to longer LED life.

Common pitfalls (and simple guardrails)

• Turning off lights in places that must stay lit (escape routes, machinery watch areas). Keep those on per rules.
• Wrong fixture for location. Use IP66 outdoors/wet areas; marine-rated gear where required.
• Harsh glare or color. Aim for ~4000K neutral white in accommodation; use dimming at night.
• Bypassing emergency circuits. Keep emergency and exit lighting unchanged and tested.
• Installing sensors but setting delays too long or too short. Start at 5–10 minutes and fine-tune.

One-week rollout plan

1. Count fixtures in two pilot zones (corridor + store). Note current wattage and burn-hours.
2. Swap to LED and add occupancy/daylight controls. Keep emergency lights as-is.
3. Record daily genset kWh or lighting submeter if available.
4. Enter results in the estimator and set your shipwide swap schedule.

Simple Summary

Each reefer plug is like a small constant engine on your grid. A few hundred units can equal a big generator. Measure real kW per box, find the hot runners, fix airflow or settings, and stagger defrost so peaks do not force another generator online. Small per unit wins scale to big daily dollars.

Best targets this week

• Count live plugs per bay by watch and compare to the power log. Lock a daily count sheet.
• Spot hot-running units: blown gaskets, blocked grilles, wrong setpoints, icing. Fix those first.
• Stagger defrost windows across stacks to trim peak kW. Avoid all-at-once spikes.
• Keep 30 to 50 cm rear and side clearance around intakes and exhausts for proper airflow.
• Do not place reefers in exhaust hotspots or full sun when alternatives exist.
• Pre-trip and pre-cool on shore when possible so shipboard pull-down is shorter.

Reefer Load Estimator

Enter units on power and average kW per unit. Add a small per unit reduction to see the savings.

Use real measurements if you can. Even a clamp meter sample across a few plugs gives a better average.

Simple reefer log (copy these fields)

Sample a few per bay each watch. You will quickly see which units run hot and why.

Common pitfalls and simple guardrails

• Wrong baseline: assuming 2.75 kW is always right. Fresh fruit vs frozen cargo draw very differently.
• All defrosts at the same time. Stagger windows to reduce peak load and spare a generator start.
• Blocked intakes and exhausts. Keep grilles clear and leave airflow gaps between units.
• Door openings without need. Coordinate checks to limit repeated openings on the same box.
• Hot spots on deck. Avoid placing boxes near hot exhausts or in stagnant air pockets.
• Claims risk. Do not chase kW at the cost of temperature control. Product quality comes first.

One-week rollout plan

1. Day 1: count live plugs and estimate total kW with current average per unit.
2. Day 2: sample 10 to 20 units with a clamp meter by bay. Flag hot runners.
3. Day 3: fix quick items: gaskets, obstructions, wrong setpoints. Shift any boxes from hot spots.
4. Day 4: stagger defrost cycles by stack. Log peak kW before and after.
5. Day 5 to 7: resample, update averages, and enter numbers in the estimator. Decide next voyage standard.

Simple Summary

OPS is cheaper when the local electricity price (plus OPS fees) is lower than what your auxiliary engines really cost per kWh (fuel + carbon + lube/O&M). A quick check: calculate your genset $/kWh, add OPS fees to the port’s grid $/kWh, and compare. If OPS wins, plug in; if not, run the genset.

OPS vs Genset Cost Calculator

Match currencies across all fields (e.g., all in USD).

Carbon price applies to ship-generated kWh at berth under many regimes; shore power typically shifts emissions to the grid. Always follow your exact reporting rules.

Practical notes

• Hours matter: High connection fee over a short stay can tilt the result back to gensets.
• Load factor: If you run an extra DG just to cover peaks, OPS can win even at higher $/kWh.
• Carbon accounting: If you pay for CO₂ at berth, add it to genset side only.
• Check voltage/frequency: Verify compatibility and cable/plug capacity before arrival.
• Noise and port credits: Some ports reduce fees for OPS calls. Ask the agent in advance.

One-week rollout plan

1. Collect last month’s aux SFOC, fuel price, and any carbon cost you pay.
2. Ask top 3 ports for grid tariff, OPS surcharge, and connection fee.
3. Run the calculator with your real hotel load and typical berth hours.
4. Publish a short OPS decision rule for the bridge team (plug-in threshold).

Simple Summary

A small battery covers short power spikes so you don’t start another generator. That saves fuel, avoids low-load running, and gives a quiet spinning-reserve while a DG starts. Size it for your typical peak size and duration, then check the battery’s “C-rate” so it can deliver the power safely.

Where batteries help most

• Berth peaks: cranes, reefer plug-in waves, HVAC steps.
• Maneuvering: thruster bursts and short hotel spikes.
• Ride-through: hold load for 20–60 s while a standby DG starts.
• Low-load avoidance: keep one DG near its sweet spot instead of two idling.

Battery Sizing & Savings Estimator

Enter a typical peak to shave and your cost of ship-generated kWh. We assume 92% round-trip efficiency and a usable SoC window of 70% (20% to 90%).

Result assumes full recharge between events. Keep a small energy margin for ride-through and aging. Always follow class and maker guidance.

Common pitfalls and simple guardrails

• Too small on energy: Size for your longest typical peak and keep 10–20% headroom.
• Ignoring C-rate: Check that Power ≤ C-rate × Energy. If not, add energy or pick a higher-C battery.
• Thermal and ventilation: Follow enclosure cooling and fire safety rules for your class society.
• No recharge plan: Ensure chargers or the running DG can refill between events.
• Wrong location: Keep away from heat, water ingress, and critical escape routes unless approved.

One-week rollout (pilot)

1. Export one week of power-log data to find typical peak size and minutes above your DG threshold.
2. Run the estimator and draft a spec for required kW and kWh, plus enclosure and class notes.
3. Ask two vendors for a modular BESS quote with marine approvals for your flag/class.
4. Publish a simple rule for the ECR: battery covers peaks up to X kW for Y min before starting the next DG.

Simple Summary

Target the few tasks that cut motor amps right away. Clean heat exchangers and coils so chillers and fans do less work. Fix chilled water ΔT so pumps and compressors slow down. Stop compressed air and steam leaks so compressors and boilers rest. Align belts and bearings to trim hidden friction. Calibrate sensors so you’re not cooling or heating more than needed.

Biggest wins this month

Scroll sideways on small screens to view all columns.

Maintenance Savings Estimator (amps to dollars)

Enter a motor you maintain, then compare amps before and after. Uses 3-phase kW ≈ √3 × V × I × PF × η.

Use your meter values where possible. Defaults for PF and efficiency are typical but can be adjusted.

Simple before and after log

Scroll sideways on small screens to view all columns.

Common pitfalls and simple guardrails

• Cleaning too hard and bending coil fins. Use proper combs and low pressure.
• Restoring ΔT by closing valves without checking comfort. Verify room temps and humidity.
• Lubing bearings with the wrong grease. Follow maker spec and purge old grease if required.
• Ignoring lockout tagout. De-energize and isolate before hands go in.
• Skipping sensor checks. A bad thermostat can waste far more than a dirty filter.

One-week rollout plan

1. Pick five motors that run many hours per day. Record amps and any pressure or ΔT tied to them.
2. Do the quick wins: strainers, coils, belts, alignment, leaks, gasket fixes.
3. Re-measure amps and enter in the estimator. If savings are clear, add to the PM schedule.
4. Publish a one-page checklist on the bridge or in ECR so the team keeps the gains.