Holistic approach to achieving low-energy, high-rise residential buildings

Abstract

As codes and standards evolve toward low- or net zero–energy buildings, the practicality of achieving these targets in high-rise concrete construction gets increasingly challenging. High-rise residential buildings are becoming more common as cities redevelop and add density. Current design and construction practice for high-rise multi-unit residential buildings present a number of constraints with regard to achieving high levels of energy performance. These practice issues typically include (a) the desire to maximize glass to enhance marketability, daylight, and views; (b) the desire to provide access to the outdoors via extended balconies; (c) the need for Code-mandated non-combustibility and life safety requirements; (d) a preference for building systems that minimize exterior construction access and streamlines construction sequencing; (e) the adoption of increased structural load requirements; and/or (f) the drive to minimize initial capital costs. The outcome of these combined constraints is often poor energy efficiency, with the burden of higher operating costs deferred to future owners. There has been significant industry discussion on the poor energy performance of this class of building, but there is very little guidance or long-term factual strategic information beyond broad principles of minimizing glazing areas, maximizing glazing performance, increasing airtightness, and adding more insulation to opaque areas. This article explores the prospect of energy use becoming a primary consideration in high-rise residential buildings and what that will likely mean for the typical competing constraints mentioned earlier. This article utilizes the current common construction practices for concrete-framed, high-rise residential buildings in heating dominated climates (ASHRAE Zones 4 to 7) as a baseline to evaluate the impact of the interconnected variables related to reducing overall heating energy use. The objective is to weigh the impact of individual improvements against integrated bundles of measures to develop a roadmap and a better understanding of a practical path toward low-energy, high-rise residential buildings. The article focuses on solutions related to building envelope performance but from a holistic perspective that recognizes the interaction and contribution of mechanical systems typical of this construction type. The building envelope parameters covered includes glazing performance (for both conventional and innovative technologies) and opaque wall performance (with a focus on specific details to reduce thermal bridging rather than increasing insulation levels). The analysis presented draws upon three-dimensional thermal modeling, whole building energy analysis, field testing and monitoring, and typical construction costs. The goal is to develop realistic targets for high-rise buildings and identify improvements that can be arrived at by market forces rather than those that can only be realized through more stringent and enforceable codes and standards.

Facades-as-a-Service: The Role of Technology in the Circular Servitisation of the Building Envelope

“…Currently, the building industry in general and the façade industry specifically are characterised by a large number of small to medium enterprises working on different levels of gradual technological innovation and improvement. In terms of energy performance, the incremental improvement provided by better insulation or slightly more efficient heating and cooling systems has been increasingly encountering the economic law of diminishing returns [53][54][55]. Such diminishing returns become even more apparent when one considers the increasing value of larger volumes-or diversity-of material resources embedded in products, or the use of rare earth metals and other critical materials which are subject to limited global supply while crucial in the manufacturing of clean energy and smart building technologies [56][57][58][59][60][61][62].…”

The Effect of Balcony Enclosure Retrofits on the Performance of MURBs

“…In MURBs, the performance of the envelope can be significantly compromised by concrete balconies which are constructed as an extension of floor slabs (Cianfrone, Roppel, & Hardock, 2016) and in the heating season, this means that a significant amount of heat can be lost through the slab. According to Ge, McClung and Zhang, 2013, the impact of thermal bridging through a balcony slab has the potential to raise the U-value of a building façade for a typical floor by 8.9% to 18.5% compared to an assembly with a thermal break.…”

Discussion on the network for environmental quality management

“…Yet we postulate that this type of heating should be located on interior walls because the floor location requires using a protective layer that increases the operating temperature of the heating medium and introduces a time delay in controlling indoor temperatures. 3 Thermal mass contributions should be optimized with surface hydronic heating/ cooling. This, in turn promotes the use of water source heat pump technology.…”

“…1 During this 40-year period, however, the quest for a sustainable built environment brought dramatic changes in the process of residential construction. 2,3 While the work on development of new…”