Integrated seismic and energy retrofitting of existing buildings: A state-of-the-art review

Ageing of the building stock is an issue affecting many regions in the world. This means a large proportion of existing buildings being considered energy inefficient, with associated high energy use for heating and cooling. Through renovation, it is possible to improve their energy-efficiency, hence reducing their significant impact on the total energy household and associated greenhouse gas emissions. In seismic regions, additionally, recent earthquakes have caused significant economic losses, largely due to the vulnerability of older buildings not designed to modern standards. Addressing seismic and energy performance by separate interventions is the common approach currently taken, however to achieve better cost-effectiveness, safety and efficiency, a novel holistic approach to building renovation is an emerging topic in the scientific literature. Proposed solutions range from integrated exoskeleton solutions, over strengthening and insulation solutions for the existing building envelope or their replacement with better materials, to integrated interventions on horizontal elements like roof and floor slabs. To identify pathways to combined seismic and energy retrofitting of buildings, a state-of-the-art review of all materials and solutions investigated to date is presented. This is followed by a critical analysis of their effectiveness, invasiveness, building use disruption as well as their impact on the environment. The assessment of current combined retrofitting research highlights a great potential for their application, with a potential to provide cost-effective renovation solutions for regions with moderate to high seismic risk. Still, to-date there is a lack of experimental research in this field, a need for further work on truly integrated technologies and their validation through applications on existing large-scale buildings. Moreover, there is a need for adequate design methods, regulations and incentives that further the implementation of integrated retrofitting approaches

Assessment of Energy-Efficient Building Details for Seismic Regions

This open access book presents a methodology for the assessment of structural building details, taking into account the contemporary guidelines for earthquake-resistant and energy-efficient buildings. A review of structural details for energy-efficient buildings revealed that in some cases the structural system is interrupted, leading to solutions which are not suitable for earthquake-prone regions. Such typical examples would be the use of thermal insulation under the building foundation and reduction of the load-bearing elements’ dimensions – also at the potential locations of plastic hinges which are crucial for the dissipation of seismic energy. The proposed methodology of assessment favours a collaboration of architects, engineers, contractors and investors in the early stage of building design. By this the methodology enables efficient decision-making and contributes to a selection of optimal building structural details. The book starts by presenting the typical structural details of the thermal envelope of energy-efficient buildings together with the scientific background required for understanding the process of detail development from all the relevant aspects. Over 20 examples of most frequent details are described and analysed to raise awareness of the importance of earthquake resistance, sustainability, energy-efficiency and thermal comfort for users

Assessment of Energy-Efficient Building Details for Seismic Regions

This open access book presents a methodology for the assessment of structural building details, taking into account the contemporary guidelines for earthquake-resistant and energy-efficient buildings. A review of structural details for energy-efficient buildings revealed that in some cases the structural system is interrupted, leading to solutions which are not suitable for earthquake-prone regions. Such typical examples would be the use of thermal insulation under the building foundation and reduction of the load-bearing elements’ dimensions – also at the potential locations of plastic hinges which are crucial for the dissipation of seismic energy. The proposed methodology of assessment favours a collaboration of architects, engineers, contractors and investors in the early stage of building design. By this the methodology enables efficient decision-making and contributes to a selection of optimal building structural details. The book starts by presenting the typical structural details of the thermal envelope of energy-efficient buildings together with the scientific background required for understanding the process of detail development from all the relevant aspects. Over 20 examples of most frequent details are described and analysed to raise awareness of the importance of earthquake resistance, sustainability, energy-efficiency and thermal comfort for users

A computational and empirical analysis of the thermal performance of insulating concrete formwork

The research presented in this EngD thesis focused on Insulated Concrete Formwork (ICF), a site-based, Modern Method of Construction (MMC). An ICF wall consists of modular prefabricated Expanded Polystyrene Insulation (EPS) hollow blocks and cast in situ concrete. The blocks are assembled on site and the concrete is poured into the void. Once the concrete has cured, the insulating formwork stays in place permanently, providing very low U-values and high levels of airtightness. ICF is often thought of as just an insulated panel acting thermally as a lightweight structure. There is a view that the internal layer of insulation isolates the thermal mass of the concrete from the internal space and interferes with thermal interaction. Despite evidence of ICF’s enhanced thermal storage capacity (compared to a lightweight timber-frame panel with equivalent insulation), there is still a gap in understanding when attempting to quantify the effect of the thermal mass within ICF.Using computational analysis (Building Performance Simulation - BPS) and empirical evaluation (monitoring data), the aim of the EngD research was to analyse the aspects that affect the thermal performance of ICF; to develop an understanding about its thermal behaviour and its response to dynamic heat transfer; and, to investigate how the latter is affected by the inherent thermal inertia of the concrete core. [Continues.]</div

Analytical and Experimental Evaluation of Precast Sandwich Wall Panels Subjected to Blast, Breach, and Ballistic Demands

Due to heightened security concerns federal as well as many public facilities require some level of blast design, whether it be intentional or accidental. In addition, with the increasing cost in utilities and continuous rise in global warming, a movement has begun to streamline the construction process and limit the environmental footprint of every building. In response, the federal government now requires that all government buildings not only be designed for blast loads, but also sustainability.Insulated wall panels are capable of meeting both the blast and sustainable requirements due to the inherit strength of a reinforced concrete slab and the thermal resistance provided from the insulating layer; however, limited experimental testing is available to prove that insulated wall panels are an ideal system for both blast and sustainability. The objective of this research is to develop the tools to design a blast and ballistic resistant insulated wall panel system. As part of this research, experimental tests were conducted on insulated panels to validate models developed to predict panel behavior observed. Using the results of the research an approach was developed to create a 1) Thermally efficient, 2) Blast Resistant, 3) Spall/Breach Resistant and 4) Ballistic Resistant panel.Insulated wall panels are inherently thermally resistive due to the insulating foam located between the two layers of concrete. Parametric studies were performed via analytical calculations to determine the efficiency of the wall system. The calculations indicated that the insulating layer is fundamental to the resistance of the panel; an 8in. solid concrete panel had a thermal resistance of less than 10% of a panel 2in. of insulation sandwiched between two 3in. concrete wythes. Additionally, the parametric study indicated that the shear connectors located between the interior and exterior wythes can have a significant effect on the overall panel thermal resistance due to the thermal bridging phenomenon. Three panels were modeled with identical layout and wythe connectors with identical dimensions but different material: concrete, steel, and low-conductive material. The panel with concrete and steel wythe connectors saw a reduction in thermal resistance compared to the low-conductive material of nearly 78% and 62%respectively. Thus, to decrease the panel resistance while maintaining strength, a strong thermally resistive material must be used as a shear connector.To improve the response to far-field detonations, experimental tests were performed on small solid panels as well as larger insulated panels. Locally unbonding the small solid panels allowed the panel to reach support rotations past the 10° specified by the United States Army Corps of Engineers as the highest threat level while the bonded panels reached less than 5° before softening. Additionally, testing of insulated wall panels revealed that the panel behavior is highly dependent on the shear tie constitutive property and location along the span. A numerical model was created to predict the behavior of an insulated and as a result, a new shear tie was developed to improve the flexural response of the panel while at the same time, decreasing the production cost.To assess the response of insulated wall panels to close-in detonations, experimental tests and numerical models were conducted. The tests revealed that the insulation results in a detriment to panel performance as a panel with 2in. of insulation sandwiched between two 3in. thick concrete wythes breaches the exterior wythe while a 6in. thick solid concrete panel does not breach under the same demand. As the insulating layer thickness is increased, the panel does not breach due to the increased standoff created by the additional thickness. Additionally, the empirical formulas developed by the Unified Facilities Criteria for solid panels were shown to be inaccurate when used for insulated wall panels, while numerical simulations were able to bound the response of an insulated wall panel.To investigate the performance of insulated wall panels to ballistic and fragment demands, a probabilistic method was developed. The method results in the creation of fragility curves allowing a designer to assess the probability of perforation and residual velocity for a given threat at any wall thickness. Additionally, the likelihood of injury occurring to personnel behind the wall panel was assessed by using organ threshold tolerances provided in literature. Using the method developed, engineers can design the thickness of an insulated wall panel to achieve an acceptable probability of occurrence for injury.Finally, all of the material learned through the first four stages were combined to create a comprehensivedesign example. An 8in. thick panel with 2in. of insulation was designed using the newly designed shear tie as well as a ductile shear tie with the same strength, and then subjected to the demands reviewed throughout the research project. The tie system allowed the wall to reach a support rotation of 10° while behaving in a moderate to heavy damage level when subjected to the far-field detonation demand. From the conclusions of the close-in detonation study, the panel is known to breach under the load prescribed. Ballistic fragility curves were developed showing that the panel stops a low threat ballistic with 100% certainty, but under a high ballistic threat the projectile has an 86.5% chance of perforating the wall system. For the fragmenting munition considered in the study, the wall system has a 15.4% chance of causing injury to personnel behind the wall. Finally, by using the new shear tie system developed, the wall system results in a reduction of less than 3% in the total R-value when compared to an insulated panel without thermal bridges due to the low thermal conductivity of the shear tie material

Full Proceedings, 2018

Full conference proceedings for the 2018 International Building Physics Association Conference hosted at Syracuse University

Risk identification in the early design stage using thermal simulations—A case study

The likely increasing temperature predicted by UK Climate Impacts Program (UKCIP) underlines the risk of overheating and potential increase in cooling loads in most of UK dwellings. This could also increase the possibility of failure in building performance evaluation methods and add even more uncertainty to the decision-making process in a low-carbon building design process. This paper uses a 55-unit residential unit project in Cardiff, UK as a case study to evaluate the potential of thermal simulations to identify risk in the early design stage. Overheating, increase in energy loads, carbon emissions, and thermal bridges are considered as potential risks in this study. DesignBuilder (DesignBuilder Software Ltd., Stroud, UK) was the dynamic thermal simulation software used in this research. Simulations compare results in the present, 2050, and 2080 time slices and quantifies the overall cooling and heating loads required to keep the operative temperature within the comfort zone. Overall carbon emissions are also calculated and a considerable reduction in the future is predicted. Further analysis was taken by THERM (Lawrence Berkeley National Laboratory, Berkeley, CA, USA) and Psi THERM (Passivate, London, UK) to evaluate the thermal bridge risk in most common junctions of the case study and the results reveal the potential of thermal assessment methods to improve design details before the start of construction stage

Business models to accelerate uptake of domestic heat efficiency and decarbonisation measures

Decarbonising the heating of existing residential buildings is a key sustainability challenge. Improving building thermal efficiency is a low regrets approach: reducing the capacity and cost of required new renewable sources and reducing fuel poverty. However, retrofitting energy efficient measures in the owner-occupier sector is difficult, facing challenges of low homeowner engagement, high costs and disruption. This dissertation applied case study methodology to consider how business model innovation can accelerate energy efficiency and decarbonisation retrofit implementation in an area of south Glasgow, UK. Using an established conceptual framework of retrofit business models, this research applied an exploratory case study approach to examine drivers and barriers to retrofit in a specific physical and social context. Findings were synthesised in an outline business model suitable to the case study area. Semi-structured interviews with professionals were used to strengthen the transferability of conclusions. Current homeowner decision making was found to be focussed on cost and payback. The potential value of improved comfort may be underestimated by homeowners, especially by occupants of traditional constructions. Coronavirus ‘work from home’ policies have changed younger homeowner attitudes towards home heating improvements. Homeowners indicate interest in advanced, independent and personalised energy assessment. Previous research into the importance of interpersonal trust was reinforced with the discovery of an online social media group with a strong local influence on tradesperson selection. An innovative business model is proposed in response to the case study findings. Policy recommendations are put forward, with particular relevance to emergent minimum energy efficiency standards for the owner-occupier sector. Further research needs are identified