🔴 The 'Sieve'
No external insulation, old aluminium frames, draughts everywhere. Requires enormous amounts of energy.
Case Study: The 10x10 Model in 3 Greek Cities
To keep our comparison fair, we set some absolutely fixed rules (the experiment's assumptions).
We will examine the home in two "versions": The "Sieve" (Old Home) - no external insulation, old aluminium frames, draughts everywhere, requiring enormous amounts of energy. And the "Thermos" (Properly Insulated) - with 10 cm external insulation, perfect airtightness (low ACH), energy-efficient glazing and roof insulation.
The Experiment's Data
The Home: 100 m² area, 3 m ceiling height. Thermostat permanently
at 21°C all winter.
The Heating System: A modern Heat Pump with an average
seasonal COP of 3.0. For every 1 kW of electricity it burns, it delivers
3 kW of heat into the home.
Electricity Price: A realistic average of
€0.16/kWh (including taxes and network fees).
🟢 The 'Thermos'
Has 10 cm external insulation, perfect airtightness (low ACH), energy-efficient glazing and roof insulation.
The 3 'Arenas' of the Test (Degree Days)
We send our home to 3 cities with completely different climates, measuring winter severity with Heating Degree Days (HDD), as we learned in the previous article:
🏝️ City 1: Heraklion, Crete (Zone A)
Mild winter, few cold snaps. About 800 HDD. 🔴 Uninsulated "Sieve": needs 8,000 kWh of energy, pump burns 2,666 kWh electricity → ≈ €426 per year. 🟢 Insulated "Thermos": needs 1,500 kWh, pump burns 500 kWh electricity → ≈ €80 per year.
🌊 City 2: Thessaloniki (Zone C)
Classic, damp and cold winter. About 1,900 HDD. 🔴 Uninsulated: 19,000 kWh energy, pump 6,333 kWh → ≈ €1,013. 🟢 Insulated: 3,500 kWh, pump 1,166 kWh → ≈ €186.
🏔️ City 3: Florina (Zone D)
Greece's "North Pole". Heavy winter with months of frost. About 2,700 HDD. 🔴 Uninsulated: 27,000 kWh energy, pump 9,000 kWh → ≈ €1,440. 🟢 Insulated: 5,000 kWh, pump 1,666 kWh → ≈ €266.
The 3 Enormous Lessons from the Table
If you study the numbers carefully, you will realise the absolute truths of energy saving:
🌍 1. Geography Is Merciless
The exact same uninsulated home costs €426 to heat in Crete, but €1,440 in Florina! The weather punishes construction mistakes more harshly as you move north (or to higher altitude).
🛡️ 2. Insulation Is the 'Absolute Equaliser'
See the stunning paradox: a properly insulated home in freezing Florina costs €266 per year. An uninsulated home in sunny Crete costs €426. Proper shielding beats climate! You can live in the snow and pay less than someone who lives by the sea and gets battered by the north wind through old windows.
⚡ 3. The 'Expensive Electricity' Myth
Many complain that "heat pumps burn too much electricity". The table proves the machine is not at fault. The pump works flawlessly. But if you install it in an uninsulated Thessaloniki home, you will be asked to pay over €1,000. If you insulate first and then install the pump, the cost "collapses" to under €200 per season.
The Pillar's Final Conclusion: Never buy the heating system before "fixing" the building's shell. The euros are not lost in the boiler; they're lost through the walls, glazing and gaps. Keep the heat inside, and no climate will ever frighten you again!
Related Articles
Heating Degree Days (HDD) Smart thermostats: How much electricity do they save in an insulated home? Why theoretical consumption differs from the bill User behaviour: The 'human factor' in consumption
Ventilation, Airtightness & Real Consumption: Climate Control
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