AC savings methodology: how Voltvert reduces energy use by 30–50%

An air conditioner's electricity consumption is determined to first order by two things: the temperature difference it must maintain against outdoor conditions (the lift), and the number of hours it runs. Voltvert addresses both.

The physics — why setpoint and runtime dominate

Setpoint sensitivity — the 8–10% per °C rule

For a fixed outdoor temperature, reducing the indoor setpoint by one degree increases the cooling load by roughly 8–10%. The effect is well-documented by public authorities and compounds when users cool two or three degrees below a reasonable comfort band.

• Agencia Andaluza de la Energía: approximately 8% additional energy per °C below the reference setpoint.
• European Commission and IEA ("Playing My Part", 2022): setting AC 1°C warmer reduces electricity consumption by up to 10%.
• Peer-reviewed mini-split study: 13.5% energy reduction when raising setpoint from 21°C to 22°C; 10.7% at 23°C to 24°C — consistent with the 8–10% per °C range under laboratory conditions.

Compounded across a 3–4°C range — typical guest behaviour at 16–20°C versus Voltvert's cap at 22–25°C — this alone produces 25–40% savings in AC electricity consumption.

Runtime reduction — timed shutoff

A typical rental unit has a guest in the room approximately 60–70% of a 24-hour day. The rest of the time, if the AC is running, it is cooling an empty space. Voltvert introduces non-negotiable pause windows — for example 14:00–17:00 when guests are typically out, or 01:00–06:00 at night.

• An AC running 10 hours per day cut to 6–7 hours equals a 30–40% runtime reduction.
• Because the AC still reaches comfort during occupied hours, guest comfort is preserved.
• On top of setpoint savings, runtime reduction typically adds 10–20 percentage points.

Why combining the two levers is non-linear

The two levers multiply rather than add. If setpoint enforcement saves 35% of the baseline, and timed shutoff saves 20% of what remains, total savings are: 1 − (1 − 0.35) × (1 − 0.20) = 48%. This is why the 30–50% band is achievable in realistic operating conditions rather than only in edge cases.

Baseline unit economics

All scenario calculations build up from a single unit baseline. These assumptions are deliberately conservative and can be replaced with the buyer's own numbers during a pilot.

The gap between the reasonable-use baseline and the abuse uplift is what Voltvert recovers. In realistic mixed-portfolio operation, 30–50% of that gap converts to savings.

Four buyer scenarios

Each scenario uses the baseline from Section 2. Savings percentages apply to the scenario-specific baseline — they represent the middle of the evidence band from Section 1, not a best case.

Scenario A — Small Airbnb host (2–6 units)

Single owner, self-managed properties. Absorbs the full electricity bill directly.

Scenario B — Property manager (20–50 units)

Managing a mixed portfolio on behalf of owners. Utility cost competes with cleaning and commission.

Scenario C — Hotel / aparthotel (40+ rooms)

Room-scale deployment. Utility bills are a line item the general manager watches monthly.

Scenario D — Extreme-abuse (worst case)

Summer peak, coastal location. Guests routinely run 16°C all day with windows open or while absent.

Sensitivity analysis

Three variables shift the numbers meaningfully: electricity price, climate severity, and guest behaviour. The table below shows how the Property Manager scenario (B) responds to electricity price.

Electricity price sensitivity

Savings are denominated in kWh first, euros second. When electricity prices rise, payback accelerates.

Climate and cooling season

A 90-day season (northern coasts) scales savings down approximately 25%. A 150-day season (islands, southern coasts) scales them up approximately 25%. The per-unit number stays proportional — percentage savings are largely climate-independent.

Guest behaviour mix

• Conservative (10% abuse, mostly responsible guests): expect 20–30% savings — floor of the range.
• Typical (25% abuse): 35–45% savings — centre of the range.
• High-abuse portfolio (40%+ of stays at 16–18°C, 24/7 runtime): 50–70% savings — top of the range.

Verification — running a pilot

The methodology above is defensible, but for any serious buyer the right question is not "do we believe the numbers" but "does it work in our units." The protocol below answers that in 30 days.

What the pilot normalises for

• Outdoor temperature — use local CDD (base 18°C).
• Occupancy — kWh per guest-night, not kWh per calendar day.
• Unit size and insulation — pair comparable units; do not compare a 25 m² studio to an 80 m² apartment.
• Electricity price schedule — use the same €/kWh in both periods for a fair comparison.

What the pilot does not claim

• Sub-kWh precision. The goal is a 20–40% band, measurable at the meter. Laboratory-grade accuracy is not necessary to make the financial case.
• Comfort-neutral on 100% of stays. Approximately 1–2% of guests actively want 17°C; Voltvert redirects them to 22°C. The savings model accepts a small rate of polite guest friction in exchange for system-wide gains.