Comparative assessment of insulating materials on technical, environmental and health aspects for application in building renovation to the Passive house level
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Over the last 30 years, the requirements for the thermal insulation of buildings in the Netherlands have been increased. In 2006, the primary energy demand for space heating was 660 PJ. The fact that this 660 PJ is approximately 20% of the total Dutch primary energy use strongly indicates the importance of improved thermal insulation of the existing building stock. Insulating an existing building with thermal insulation can be complex, costly and time consuming. During a building renovation or refurbishment, the applied thermal insulation must provide a high level of thermal resistances to the building envelope, in order to lower the energy demand for space heat as far as possible. The Passive house concept defines such levels of insulation for both new and existing buildings, resulting in thick layers of insulating materials. The Passive house concept is an integral concept in which next to thermal insulation, also ventilation standards are prescribed with which a solid basis is laid for energy efficient building renovations. Before the Passive house concept is used on a large scale, the technical, environmental and health aspects of the insulating materials used within the concept must be investigated. The main research question therefore is: “Which insulating materials are most suitable to reach the energy efficiency level of a Passive house, when taking technical, environmental and health aspects into account?” By means of interviews with producers and experts in the field, literature research and a quantitative assessment of LCA studies, it was found that glass‐ and rock wool (mineral wool) together with Expanded Polystyrene (EPS) are the most suitable insulating materials for application within Passive house renovation. This is because of the fact that for both mineral wool (glass wool and rock wool) and EPS, multiple end‐of‐life scenarios are available. EPS can be recycled or incinerated, whereas mineral wools can be recycled into new mineral wool, but also into other products such as facade panels or sound insulation. For both EPS and mineral wool recycling facilities are already in place and used in practice. Materials such as PUR/PIR and PF‐foam do not have these recycling options yet, which only leaves incineration as the end‐of‐life solution. In the study also hemp‐ and flax wool were examined. It turns out that the environmental impact of these materials is often higher than that of EPS and mineral wool. Additionally, the use of polyester support fibres in hemp‐ and flax wool makes it impossible to recycle these fibres, leaving incineration as the only end‐of‐life option. From a health point of view, both EPS and mineral wools should be improved further. Especially the formaldehyde based binders used in mineral wool and the fire retardant hexabromocyclododecane used in EPS should be replaced by other materials on a short term. The developments thereof are already in progress and in an advanced phase. Besides the LCA assessment, two other quantitative assessments were made. The focus of both assessments was the insulation of existing cavity walls. The first assessment provides insight into the amount of insulating material needed for both normal and Passive house renovation. The second assessment estimates the savings of insulating empty cavity walls. The results of this assessment show that filling the empty cavity walls in the Netherlands would require approximately 10 million m3 of insulating materials versus 54 million m3 for renovation to the Passive house level. The estimated savings of insulating the existing empty cavity walls by filling the air cavity, is about 69 PJ/year which annually avoids the emission of 3.9 GtCO2 –eq. If the cavity wall would be renovated to a Passive house level, the savings and avoided emissions would be 96 PJ/year and 5.3GtCO2 eq. In this estimation, the energy and GHG‐emissions of the insulating materials are discounted over a lifetime of 50 years. The emissions and energy use during the renovation could not be taken into account, because data thereof was not available. Overall, the emissions and energy use of the insulating materials is compensated within a year by the emission reduction and energy savings of insulation the existing walls.