How Many AC Units Does a 2-Storey 70 m² Home Need? Capacity Guide for Bekasi

One post-move cost that often gets left out of the budget is AC, buying units, installation, and the ongoing electricity. For a 2-storey house around 70 m² in Bekasi, where daytime temperatures average 30–33°C with 70–80% humidity, getting the sizing wrong means either a room that never fully cools down, or a bill that climbs every month for no obvious reason.

Before you shop, there are a few things worth calculating first.

The Basics: BTU and PK for a Tropical Climate

AC capacity is measured in BTU/hour (British Thermal Units) or, as it's commonly called in Indonesia, PK (from the Dutch Pferdestarke). The conversions: 1 PK ≈ 9,000 BTU/hr, 1.5 PK ≈ 12,000 BTU, 2 PK ≈ 18,000 BTU.

The baseline rule for tropical climates: 500–600 BTU per m² of room area. A 15 m² room needs roughly 7,500–9,000 BTU, which puts it squarely in the 1 PK range. But a few multipliers apply:

• Upper floors (absorb roof heat): add 10–15%
• Rooms exposed to direct sunlight for more than 4 hours/day: add 10%
• Rooms with heavy electronics (large TV, gaming PC): add 5–10%
• Rooms regularly occupied by more than 2 people at once: add 5%

Recommended AC Capacity by Room — Emerald 70 Typical Layout

For a 2-storey home with 70 m² of built-up area, the typical layout breaks down roughly like this:

Room	Est. Area	Recommended Capacity	Notes
Living / family room (ground floor)	~18 m²	1.5 PK	First priority
Master bedroom (upper floor)	~12 m²	1 PK	Upper floor, consider +10%
2nd bedroom / guest room (upper floor)	~9 m²	¾ PK or 1 PK	Depends on sun orientation
Home office (optional)	~6 m²	½ PK or 1 PK	If used full-day

Total recommendation: 3–4 AC units for a fully conditioned 2-storey 70 m² home. Many owners start with 2 units (living room + master bedroom) and add more as needed.

Inverter vs Standard: It's Not About Which Is "Better"

An inverter AC modulates its compressor speed based on cooling demand, rather than cycling on and off like a standard unit. The result: 30–50% lower electricity consumption over time, quieter operation, and longer compressor life.

The upfront cost is 30–60% higher. But if you're running AC 8–10 hours a day, which is common in Bekasi, that premium typically pays for itself within 18–24 months from electricity savings alone.

When does a standard (non-inverter) unit still make sense? For rooms used fewer than 4 hours a day, a rarely occupied guest room, for instance, the inverter's ROI timeline stretches long enough that the standard unit can be the more cost-efficient pick.

Indoor and Outdoor Unit Placement — Common Mistakes

The indoor unit should be mounted on the wall that faces the largest area of the room, not tucked into a corner. Airflow needs a clear path to reach the whole space without being blocked by large furniture.

The outdoor unit is more critical to get right. In cluster housing, outdoor unit locations are usually designated on a specific side of the home (typically the rear or side). Avoid placing the outdoor unit where it:

• Gets direct sunlight all day, efficiency drops noticeably when the heat exchanger is fighting the sun
• Sits in a narrow, enclosed space with no airflow, heat the unit is trying to expel gets trapped, making the compressor work harder
• Points toward a neighbor's window or ventilation opening, heat and noise complaints follow

For upper-floor units, mounting the outdoor unit on the roof deck or a wall bracket on the upper exterior is standard in modern cluster homes. Make sure any bracket is anchored to a structural wall, not GRC cladding or decorative panels.

Estimated Monthly Electricity Cost

Using PLN's R-2 tariff (3,500 VA power capacity, approximately Rp 1,699/kWh), a 1 PK inverter AC running 8 hours a day works out to:

• Average draw: ~0.65 kW × 8 hours × 30 days = 156 kWh/month
• Cost per unit: 156 × Rp 1,699 = ~Rp 265,000/month
• For 3 inverter AC units (living room + 2 bedrooms): ~Rp 600,000–800,000/month

Those numbers drop with a thermostat set to 24–26°C (not 18°C), sleep mode at night, and a timer schedule. Every 1°C increase in setpoint saves roughly 6–8% on consumption.

Buying Tips: Timing and What to Watch Out For

AC sales around Eid and mid-year promotions (June–July) typically offer 10–20% discounts. That said, don't purchase units before your home is handed over, layout changes can affect placement decisions in ways that aren't apparent from a floor plan.

Avoid second-hand AC units unless the service history is fully verifiable. A worn-out compressor is invisible from the outside, and repair costs can exceed the price of a new unit.

Installation costs are frequently overlooked in the budget. For a single unit including materials (piping, wiring, brackets, insulation), expect Rp 400,000–800,000. Upper-floor installations with longer pipe runs cost more. Ask for an itemized installation quote before agreeing.