Hygrothermal Analysis of Retrofitted Buildings in the Campus of Lund University

Abstract

As climate change have become generally accepted as a potential problem, reducing the greenhouse gas emissions and global energy demand has become an important research topic. This have led to an increased interest towards the retrofitting of the existing building stock, including cultural protected buildings. Due to the cultural protection, carrying out major alteration such as exterior wall retrofits are often not possible, leaving interior retrofitting as the only option. Previous studies have however shown that interior retrofitting poses great risks with respect the hygrothermal performance. This study focused on assessing the long term performance of various energy retrofitting measures for the exterior wall and roof constructions with respect to energy- and moisture performance, window replacement was not included. Carried out for two protected buildings in the campus of Lund University, and the adaptability of the retrofitted measures towards the future climate conditions, simulated until year 2100. The economic- and environmental feasibility of the retrofitting measures was furthermore determined through LCC and LCA. Results showed the smart vapour retarder assemblies would outperform both the capillary active as well as the traditional assemblies using PE-foil, with respect to the hygrothermal performance. However, the water repellent coating showed to be vital for any of the wall assemblies to problem free. A potential reduction of the heating demand by 20-30% was shown for the retrofitted walls, while only 5% for the retrofitted roof constructions. The retrofitting measures were shown to be economic infeasible, while the wall measures were shown to be environmental feasible.

Popular Abstract

Hygrothermal Analysis of Retrofitted Buildings in the Campus of Lund University
Studying the long-term performance of applying retrofitting measures to two cultural protected school buildings with respect to moisture and energy. Long-term moisture safety and a heating demand reduction of up to 20-30% was achieved.
To carry out a retrofit on cultural protected buildings is often a risky task. The protection often contains restrictions which may prevent the use of the safer and more effective methods. Moisture problems are especially likely to occur when interior insulation is used to retrofit existing building parts. The interior insulation will change the movement of heat and moisture passing through the building parts resulting in a moisture build-up. Despite the risks associated with a building retrofit, there has in recent years been a growing interest to do so. Partly due an increased awareness concerning climate change and the potential problem it may bring, but also due to the great energy saving potential the older part of the building stock yield. This includes also retrofitting of cultural protected buildings. It is therefore of utmost importance that more focus is placed on how to solve the problems related to retrofitting using interior insulation methods.
Satisfying long-term moisture safety was however achieved using interior insulation when combined with a water repellent coating to retrofit the existing outer walls of two cultural protected school buildings at Lund University in southern Sweden. The best performing solution was a traditional glass wool installation combined with a so called “smart vapour retarder” for airtightness and drying out. A surprising discovery was the importance of the water repellent coating, as it was vital for any solution to succeed. Although the retrofitting measures showed a reduction of 20-30% and 5% respectively for the exterior wall and the roof constructions for the annual heating demand, the measures turned out to be economically infeasible. In contrast to the economic aspect, a retrofit of the exterior walls turned out to be feasible from the environmental aspect.
The objective was to assess the long-term performance of various energy retrofitting measures for the exterior wall and roof constructions with respect to the energy and moisture performance. The major focus was placed on retrofitting the exterior wall with interior insulation solutions, while a smaller focus was placed on the roof constructions. The economic and environmental possibility of the retrofitting measures were also accounted for through Life Cycle Cost and Life Cycle Assessment.
The study was carried out in six phases:
• A literature review phase, reviewing relevant literature and generation ideas.
• A project goals phase, defining the project goals, simulation cases and expected results.
• A moisture assessment phase, assessing the long-term moisture performance of the wall and roof solutions.
• A thermal bridging phase, assessing the thermal bridging effect of the approved solutions.
• An energy performance phase, assessing the long-term energy performance of approved solutions using whole-building energy simulations.
• Lastly, a feasibility phase, assessing the economic and environmental feasibility of the retrofitting measures.

• author: Jensen, Nickolaj Feldt
• supervisor: Vahid Nik
• organization: Division of Energy and Building Design
• course: AEBM01 20161
• year: 2016
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Retrofit, Interior Insulation, Hygrothermal, Energy Simulations, Life Cycle Cost, Life Cycle Assessment
• language: English
• id: 8894379
• date added to LUP: 2016-11-03 11:20:00
• date last changed: 2016-11-03 11:20:00