“…This is interesting in the context of the implication of aggressive building heat demand reduction through fabric measures (the so called fabric first strategy) which would shift the heat demand into this area even at lower outdoor temperatures, reducing the need for hybrid appliances. In the absence of large reductions in building heat demand, which has been shown to pose its own problems of cost and embodied carbon payback, 34 it is therefore reasonable to assume that demand reduction through heating efficiency will need to deliver significant proportion of the emissions reduction.Figure 3.Space heating energy demand, gas and electricity as a function of outdoor temperature. Hybrid HP size 4 kW.…”
Section: Modelled Results and Discussionmentioning
The heat decarbonisation challenge remains substantial, competing low carbon solutions such as hydrogen and heat pumps (HPs) and the entrenched position of gas combination boilers create inertia in many markets. Hybrid appliances which can directly replace gas boilers may provide a low disruption, low-cost pathway to net zero in gas-reliant markets. Emerging compact combination (CoCo) hybrid heating appliances which combine a gas combi boiler and a small HP unit in one appliance have been modelled for the English housing stock across a range of different scenarios. CoCo hybrids offer sizeable energy demand reduction of up to 60% compared to current gas boilers, also reducing peak electrical demand by 10 GW compared to air source heat pumps. The control strategy for switching between HP and gas boiler is key in determining the scale of demand reduction. Modelling sensitivity to the HP size within CoCo hybrids showed that a 50% reduction in energy demand compared to gas boilers could be achieved with a standard 2.5 kW HP. A lack of clarity in regulation and policy incentives for hybrids exists. To drive innovation and performance improvement, product regulation for hybrids needs to be improved to support decarbonisation of heat with this promising technology. Practical Application Convenient, low disruption heat decarbonisation technology is crucial to the speed of deployment necessary to achieve net zero. This article defines the size of HP necessary to achieve rapid low disruption impact and distinguishes the types of compact hybrid which can deliver the highest decarbonisation impact while minimising in house disruption and the electrical grid impact.
“…This is interesting in the context of the implication of aggressive building heat demand reduction through fabric measures (the so called fabric first strategy) which would shift the heat demand into this area even at lower outdoor temperatures, reducing the need for hybrid appliances. In the absence of large reductions in building heat demand, which has been shown to pose its own problems of cost and embodied carbon payback, 34 it is therefore reasonable to assume that demand reduction through heating efficiency will need to deliver significant proportion of the emissions reduction.Figure 3.Space heating energy demand, gas and electricity as a function of outdoor temperature. Hybrid HP size 4 kW.…”
Section: Modelled Results and Discussionmentioning
The heat decarbonisation challenge remains substantial, competing low carbon solutions such as hydrogen and heat pumps (HPs) and the entrenched position of gas combination boilers create inertia in many markets. Hybrid appliances which can directly replace gas boilers may provide a low disruption, low-cost pathway to net zero in gas-reliant markets. Emerging compact combination (CoCo) hybrid heating appliances which combine a gas combi boiler and a small HP unit in one appliance have been modelled for the English housing stock across a range of different scenarios. CoCo hybrids offer sizeable energy demand reduction of up to 60% compared to current gas boilers, also reducing peak electrical demand by 10 GW compared to air source heat pumps. The control strategy for switching between HP and gas boiler is key in determining the scale of demand reduction. Modelling sensitivity to the HP size within CoCo hybrids showed that a 50% reduction in energy demand compared to gas boilers could be achieved with a standard 2.5 kW HP. A lack of clarity in regulation and policy incentives for hybrids exists. To drive innovation and performance improvement, product regulation for hybrids needs to be improved to support decarbonisation of heat with this promising technology. Practical Application Convenient, low disruption heat decarbonisation technology is crucial to the speed of deployment necessary to achieve net zero. This article defines the size of HP necessary to achieve rapid low disruption impact and distinguishes the types of compact hybrid which can deliver the highest decarbonisation impact while minimising in house disruption and the electrical grid impact.
“…Although innovative technologies and energy efficiency solutions are widely available today, a multidisciplinary approach is essential to describe intervention scenarios in existing building structures [6]. These scenarios should not only propose measures to improve energy efficiency, but should also reveal the most effective combinations to remedy the energy degradation of existing buildings.…”
Section: Introductionmentioning
confidence: 99%
“…The third phase is the evaluation of the potential of each intervention, while the fourth phase is dedicated to the implementation of the renovation solutions, which are finally validated by the results in the fifth phase [11]. Numerous studies already provide tools and context for reducing energy consumption around the world [3][4][5][6][7][8][9][10][11][12][13][14]. Retrofitting existing structures can significantly reduce energy consumption and greenhouse gas emissions worldwide.…”
The retrofit of the most energy-intensive buildings represents an opportunity to improve their energy efficiency or to reduce their energy demand. This paper proposes combining computer-aided design (CAD) modeling and the use of energy efficiency software to build a methodology for calculating, visualizing and analyzing building parameters in order to provide retrofit scenarios. Five retrofit scenarios were implemented using the energy software, including the initial operating cost, capital cost and payback period to be evaluated. At the same time, a three-dimensional CAD model was created to perform daylighting and shading simulations to visualize and design the role of building orientation under actual use conditions. These retrofit scenarios were evaluated individually and then combined to examine their performance in terms of cost-effectiveness and energy efficiency. The simulation results show the importance of the building’s orientation, as this directly affects the thermal properties of the walls and openings, as well as the daylighting areas. The simulation results were also used to define the parameters that affect the interoperability of the retrofit solutions. Finally, in addition to the significant reduction in calculation time, the coupling of the CAD software with the energy efficiency software allowed access to information that was not available at the outset.
“…Whilst a circular retrofit approach does present potential challenges, the potential carbon benefits are significant. Li et al 3 modelled the domestic retrofit measures that are required for England to stay within carbon budgets. They found that for all eligible properties a package of retrofit measures needed to be installed in 2021, including external or internal or cavity wall insulation, double glazing and heat pumps.…”
mentioning
confidence: 99%
“…If this opportunity is missed, the future waste burden will likely be considerable. To put this into context, using Li et al 3 as a basis, a wall area of ~3 billion m 2 requires insulating, covering cavity wall, external and internal insulation. If an average thickness of 100 mm is assumed, this equates to a volume of 300 million m 3 of insulation that is required to insulate the walls of England's housing stock.…”
Building retrofit is essential to deliver decarbonisation. But its implementation could leave a legacy of waste if end of life is not considered now. Here I consider the challenges and implications of embedding circularity into building retrofit.Buildings retrofits improve energy efficiency and are an essential component of global decarbonisation plans. However, whilst many retrofit techniques will reduce energy demand in the near future, their longevity is rarely considered. This risks a legacy of waste with high recurring embodied carbon, and buildings that cannot be easily further upgraded in decades to come. To avoid this, engineers, architects, designers and builders must start now to embed a circular economic (CE) approach into building retrofit.
Typical retrofitsRetrofits usually tackle two main components: the building fabric and building services. I will focus on domestic building fabric measures. These seek to improve the thermal efficiency of walls, windows and doors through installation of insulation, double or triple glazing, and insulated doors. In temperate climates, such as the UK, building engineers and designers typically focus on reducing heat loss from the building to reduce energy demand. As temperatures rise however, they should also be aware of the post-retrofit risk of overheating in summer months and should ensure sufficient ventilation is provided.The thermal performance of building fabric retrofits typically degrades over time. For example, organic, closed cell insulation materials such as expanded polystyrene, extruded polystyrene, polyurethane, and phenolic foam, leach their foaming gases over time, reducing their thermal performance 1 . Similarly double glazing will not indefinitely retain its thermal performance. Over time glazing seals fail, which allow fresh air into the air gap between the glazing panes. This reduces thermal efficiency and can result in condensation between the glazing panes.In both cases the degradation in performance could lead to the need for replacement of insulation or glazing to optimise buildings' thermal efficiency. The degradation in performance of glazing means that windows are typically replaced after 20-30 years. While the component materials (e.g. plastic frame and window glass) can be recycled, this requires energy and supply chains to 'take-back' the materials. Glazing replacement is more frequent as the condensation highlights the degradation. But in a future net zero world, we are likely to also seek to replace insulation more often to improve building energy efficiency.The value of applying circular economy principles CE aims to keep materials at the highest value possible. In the case of a building this means retention and retrofit (rather than demolition) for as long as possible. However, we also need to consider how to keep the components and materials that are used in retrofit at the highest value possible. This means rather than recycling the materials from a window, priority should be placed on remanufacturing the window in-situ. This rete...
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