Research results: insulation | front and rear facade: wall and brackets
- Commissie Duurzaam
- 30 jan
- 5 minuten om te lezen
Bijgewerkt op: 9 feb
Table of contents of insulation
The current situation
The front and rear facades are largely made of glass. Only at the (concrete) structural brackets (known as the "console") is a concrete wall, alternately finished with a 1.60 m wide concrete gravel panel or a 40 cm wooden panel.
During the 2013 renovation, the exterior facades were renovated at the front and rear, but apart from the installation of HR++ glass, the facades were not further insulated. The thermal bridges, in particular, (see explanation in Insulation - introduction ) the consoles have not been tackled.
In February 2022, an infrared camera was used to investigate where our building loses heat and where cold enters. The camera records heat radiation and translates it into colors.
The interpretation depends on whether the shots were taken indoors or outdoors.
Outdoor recordings mean
red/yellow/orange heat loss;
blue/green well insulated
On indoor recordings it is the other way around:
blue/green = cold ingress, poorly insulated
red/yellow) = warm, well insulated
The concrete brackets —the protruding supports that support the galleries—stand out in the thermal images. Because this solid concrete extends from the interior to the exterior, it conducts heat outward and cold inward.
The problem arises because the bracket isn't thermally broken. There's also heat loss because the facade beneath the brackets only has 20 mm of cavity wall insulation.
The current facade construction with a bracket consists of:
inner layer (concrete): 70 mm;
cavity wall insulation: 20 mm;
cavity: 50 mm;
outer layer (concrete): 70 mm;
console connected to the dividing interior wall.
The Rc value of the current facade structure is 0.83. The minimum requirement for renovation according to the Building Decree is an Rc of 1.4. Therefore, the current insulation values do not meet the required energy performance standards.
Opportunities for improvement
The greatest improvement is expected from insulating the brackets. However, this is only effective if the concrete exterior wall is also insulated.
The facades
There are 2 options
Option 1 – cavity wall insulation
Insulating the air space between the building's interior and exterior walls. This can be done in the 50 mm cavity with:
· Supafil glass wool insulation; environmentally friendly, Rc value 1.5;
· pure; non-biodegradable and less environmentally friendly; Rc value 2.4.
Option 2 – Insulate the outside
This is an insulation layer on the outside of the building
Both HU students and Steeds Advies agree that exterior wall insulation will significantly improve a home's energy efficiency and thermal comfort. The Rc value increases to 5 .
With exterior wall insulation, insulation material is applied to the exterior of the building, which retains heat inside the house and reduces energy loss. The existing gravel panels must be demolished and replaced with insulation panels. This is possible in various materials.
When implementing this measure, several important points should be taken into account:
it is necessary to demolish the existing gravel panels, which entails both cost and logistical challenges and inconvenience;
The building's modifications may result in a changed appearance, for which a building inspection is required (read more about Kleiburg, a protected urban view here ).
Facade insulation - costs, subsidies, financing
Option 1: cavity wall insulation
Costs: The average price for cavity wall insulation with 50mm polyurethane foam is between €25 and €35 per m² , including installation. These costs can vary depending on various factors. The total cost is between €36,750 and €51,450.
Subsidy: The measure is eligible for a subsidy. This amounts to:
for one insulation measure: €5.25 per m2;
for two or more insulation measures: €10.50 per m2;
for a total surface area of 1470 m2 this is €7,717.50 / €15,435.
Option 2: external wall insulation
Costs: Steeds Advies estimates the costs of this insulation at €610,000.
Subsidy: The measure is eligible for a subsidy. This amounts to:
for one insulation measure: €20.25 per m2;
for two or more insulation measures: €40.50 per m2;
for a total surface area of 1470 m2 this is €29,767/€59,535.
The insulation of the facade walls can be further financed by a loan from the National Heat Fund.
Insulation of the consoles
The students consider it crucial to address the thermal bridge in the cavity wall by insulating the brackets. This reduces heat loss and significantly increases living comfort. Steeds did not investigate this because this measure was not included in their computer program (see also:The Research ).
PIR insulation was chosen as the insulation material. This was because its insulation values were good but not too thick. Insulation thickness was a key factor in determining the insulation material here due to the clearance height under the brackets. The insulation thickness chosen was 50 mm.
The cladding elements can be finished with a thin concrete top layer or a decorative concrete-look finish. This gives the cladding elements a concrete look that complements the building's design.
Due to the requirements imposed on buildings in a protected cityscape , cladding up to halfway up the consoles could be chosen. A permit will have to be applied for.
Console insulation - costs, subsidies and financing
Costs:
the costs of this intervention are estimated at €52,140 for the PIR boards and €68,760 for the concrete finish in the spring of 2024;
Per console, the procedure costs €232.50. The total cost of the procedure is €120,900.
Subsidy:
Insulation of concrete consoles is subsidized if it is part of the total insulated facade surface;
the subsidy amount for consoles is related to this and follows the rate of the building shell measure to which they belong and is therefore dependent on the choice of cavity wall insulation or external wall insulation;
only if the facade insulation and insulation of the consoles can be demonstrated as separate insulation measures, these will be considered as two measures, meaning that the subsidy amount can double ;
For a precise assessment on this point, it is recommended to contact a specialist or the RVO Counter .
Borrowing: The insulation of the facade walls can be further financed by a loan from the National Heat Fund.
Marginal notes
Casings extending halfway up the console, which can be temporarily removed for maintenance and then replaced, are technically feasible. However, this is always a custom solution: a detail must be chosen in consultation with the supplier (prefabricated casings) and the structural/building physics consultant, specifically considering disassembly.
Want to read more about insulation?
Do you have any questions, ideas or would you like to share your experiences?
Email us at duurzaamkleiburg1@gmail.com . Together we'll chart a path toward a future-proof Kleiburg.