Why thermal insulation in the facade
The exterior wall is the most influential factor in a building energy balance. Up to 40 percent of winter heat loss and summer heat gain passes through exterior walls. Without proper insulation, an air conditioner works three times as hard to maintain interior temperature.
Exterior wall thermal insulation breaks this heat bridge. It creates a resistance layer preventing heat transfer between inside and outside. Result: the AC works less, electricity bills drop significantly, and the home becomes more comfortable.
How a rear ventilated facade with insulation works
A rear ventilated facade system consists of four layers, outside to inside: cladding panels (Alucobond), air gap, thermal insulation, and structural wall. The air gap between cladding and insulation is the magic.
Hot air rises from the gap creating a chimney effect that continuously removes heat. Cladding protects insulation from direct sun and moisture. The insulation itself does the thermal work. The interior wall remains at stable temperature year-round.
- Layer 1 (exterior): Alucobond panels, climate protection
- Layer 2: 40 to 80 mm air gap, moisture drainage + heat convection
- Layer 3: 80 to 120 mm thermal insulation, rock wool or polyurethane
- Layer 4: vapor membrane on interior wall
- Layer 5: the structural wall, protected beneath the entire system
Insulation types for ventilated facades
Rock wool is the professional standard. It is non-combustible, stable over time, and offers excellent thermal conductivity values. Typical 80 to 120 mm thickness gives R-3 to R-5 thermal resistance value. Rock wool also provides acoustic insulation, reducing external noise.
EPS (sprayed polystyrene) is a cheaper alternative but less recommended. It is combustible (even when fire-treated), less durable, and adds fire risk. In new codes, combustible insulation is not allowed in high-rises. Polyurethane spray is an excellent acoustic and thermal alternative, but expensive and unsuitable for every system.
How much energy you actually save
Measurements in our projects show 25 to 35 percent savings in heating and cooling electricity costs after installing a rear ventilated facade with mineral insulation. In a typical 120 sqm home that consumed 8,000 NIS annually for electricity, savings are 2,000 to 2,800 NIS per year.
A large difference is also measured at peak load on cooling systems. An AC working at 90 percent capacity now works at 60 percent. This extends system life and reduces need for expensive upgrades. Savings accumulate beyond direct electricity bill.
ROI and payback period
The additional cladding cost due to insulation is about 150 to 250 NIS per sqm. On an 800 sqm facade, that is an additional 120,000 to 200,000 NIS. Annual electricity savings for the entire building: 80,000 to 120,000 NIS. Payback: 2 to 3 years. After that, net savings for at least another 22 years.
Additional benefit: residential buildings with high energy ratings receive higher sale prices. The Israeli real estate industry is increasingly focused on this criterion. An apartment in a building with rating A or B sells for 5 to 10 percent more than a similar apartment in a low-rated building.
Frequently asked questions
What percentage of electricity bill is saved?
On average 25 to 35 percent on heating and cooling costs. In homes consuming more energy (south-west facing facade, heavy AC use), savings can reach 40 percent. In already-efficient homes savings are less dramatic but still significant.
Does insulation suit every building type?
Yes, a rear ventilated facade with insulation suits any building type: residential, office, commercial. Adaptation in insulation thickness, type, and attachment system varies by existing structural wall. Proper design by a professional contractor is critical.
What is the difference between interior and exterior insulation?
Interior insulation reduces living space (shrinks apartments by 3 to 5 percent), does not handle structural thermal bridges, and creates condensation problems in walls. Exterior insulation solves all of these and performs thermally much better. It is the recommended professional standard.
Does this require engineering approval?
Yes, a rear ventilated facade system with insulation is part of the building envelope and requires engineering design. In new buildings the engineer plans this from the start. In an upgrade of an existing building, an engineer is needed to approve the addition and design the attachment connections. DAR GROUP always works with a structural engineer on every project.
