Emerging technologies in building envelopes

Advancements in engineering and space technology are increasingly finding application in buildings. Building envelopes are utilising components of high-technological solutions resulting in better visibility, greater light transmission, increased energy generation and storage capacity, improved shading and ventilation and integration with the external environment. This report summarises several technological advancements and suggests forthcoming directions for building envelope design. Many of the technologies presented here have been invented and developed in Australia, yet are not commonly used by the building construction industry.

Energy efficient envelope design for high-rise apartments

The energy required to create a comfortable living environment in  high-density cities in hot and humid climates usually demands a substantial electricity usage with an associated environmental burden. This paper describes an integrated passive design approach to reduce the cooling requirement for high-rise apartments through an improved building envelope design. The results show that a saving of 31.4% in annual required cooling energy and 36.8% in the peak cooling load for the BASECASE apartment can be achieved with this approach. However, all the passive strategies have marginal effect on latent cooling load, often less than 1%.

Natural and environmentally responsive building envelopes

In a context of global warming and our needs to reduce CO\d2 emissions, building envelopes will play an important role. A new imperative has been put forth to architects and engineers to develop innovative materials, components and systems, in order to make building envelopes adaptive and responsive to variable and extreme climate conditions. Envelopes serve multiple functions, from shielding the interior environment to collecting, storing and generating energy. Perhaps a more recent concern of terrestrial habitats is permeability and leakages within the building envelope. Such airtight and concealed envelopes with zero particle exchange are a necessity and already exist in regard to space capsules and habitats.

This paper attempts to acknowledge existing and visionary envelope concepts and their functioning in conjunction with maintaining a favorable interior environment. It introduces several criteria and requirements of advanced fa\acades along with interior pressurization control. Furthermore, the paper also takes a closer look at the principles of "biomimicry" of natural systems combined with the most up-to-date building materials and construction technologies, trying to integrate the notions of adaptation - where the capacity to survive depends on the ability to adjust to the environment - within the concept of technological evolution and innovation. An "adaptive" attitude in the way in which we conceive our built structures provides a conceptual basis for the advanced building design of our future, as well as one concerned about the efficient management of the available resources. Built environments of the future (in extreme climates or not) will need to respond to Renewable, Adaptive, Recyclable and Environmental (R.A.R.E.) concepts in order to coexist in a sustainable way with their surroundings.

Net Energy Analysis of Double Glazing for Residential Buildings in Temperate Climates

Energy used in buildings is a major contributor to Australia’s energy consumption and associated environmental impacts. The advent of complex glazing systems such as double glazing, particularly in northern America and Europe, has partially closed a weak thermal link in the building envelope. In milder climates, however, building envelope features may not be as effective in life cycle energy terms, i.e. including the embodied energy of their manufacture. A net energy analysis compares the savings in operational energy to the additional requirements for embodied energy, in terms of the energy payback period and energy return on investment. The effectiveness of double glazing is determined for an Australian residential building. A wide range of building operation regimes was simulated. These results support the principle of installing double glazing in residential buildings in Melbourne, Australia, at least in terms of net primary energy savings.

Evaluating rammed earth aalls: a case study

The following research has been undertaken as a response to the recent controversy regarding the suitability of rammed earth wall construction as an effective building envelope. Empirical (in-situ) measurements of temperature and heat flux are taken on the walls of an existing rammed earth building in New South Wales, Australia. An analysis is performed which examines the influence of walls, floor, ceiling and windows on the recorded temperatures within the building. It appears that diffuse sky radiation transmitted by the windows is an important factor in the summer heat load, and that night time cooling coupled with thermal mass has a valuable conditioning effect.

The influence of housing size, style and location on energy and greenhouse gas emissions

Concern about the growth of greenhouse gas emissions in Victoria has prompted the introduction of legislation to improve the thermal performance of the residential building envelope. Unfortunately, the size of the house is not considered in the rating tool that underpins the legislation. The energy embodied in the constructional materials is also not considered although it too is directly related to the size of the house. Another intrinsic factor relating residential housing energy and greenhouse gas emissions is the location of the residence and the travel preferences of the homeowner. The relationship between the operational, embodied and travel energy associated with a typical residential scenario in Melbourne over the last 50 years is examined in this paper. The analysis found that by the year 2000, the energy associated with work-related travel (44%) now exceeds the operational energy (37%). In terms of greenhouse gas emissions, the contribution from travel energy is almost double that from operational energy (28%).

Towards a renewable adaptive recyclable and environmental architecture

Research in pursuit of an effective response to the demands for a sustainable architecture has lead towards the conception of a Renewable, Adaptive, Recyclable and Environmental (R.A.R.E.) building typology. The term R.A.R.E. expresses issues that have assumed central importance in the current architectural debate. This paper establishes the principles of the typology, drawing on the contents and pedagogical methods applied in a building technology academic course, at fourth year level. The R.A.R.E methodology is presented to and explored by students in the search for a definition of an innovative architecture, which is both progressive and sustainable. The unit is structured into eight subjects: Sustainable Site & Climate Analysis; Flexible & Adaptive Structural Systems; Renewable & Environmental Building Materials; Modular Building Systems; Innovative Building Envelope Systems; Renewable & Non-conventional Energy Systems; Innovative Heating, Ventilation & Air Conditioning Systems; Water Collection & Storage Systems. Through a holistic and integrated approach, the unit presents a comprehensive overview of these ‘Sustainable Building Categories’, so that the students can produce a guide towards the design requirements of a Renewable, Adaptive, Recyclable and Environmental (R.A.R.E.) Architecture.

A roadmap to Renewable Adaptive Recyclable Environmental (R.A.R.E.) architecture

R.A.R.E. stands for Renewable Adaptive Recyclable Environmental Architecture; the acronym expresses a demand that is becoming increasingly important today in the eyes of designers and clients. The paper draws on the contents and the pedagogical methods applied in a Building Technology Unit (SRT 450) – at forth year level – at the School of Architecture and Building, Deakin University, Australia. The unit is basically structured upon eight subjects derived as relevant to the research and development for a R.A.R.E. Architecture: Sustainable Site & Climate Analysis; Flexible & Adaptive Structural Systems; Renewable Adaptive & Environmental Building Materials; Modular Building Systems; Innovative Building Envelope Systems; Renewable or Non-conventional Energy Systems; Innovative Heating, Ventilation & Air Conditioning; Water Storage & Systems. The overall objective of the unit is to present a comprehensive overview of all these Sustainable Building Categories (SBCs) so that the students can produce a guide towards the design of a R.A.R.E. Architecture. The push towards a holistic and integrated approach will contribute to the definition of an innovative architecture, which is both progressive and sustainable.

Realising air leakage in Australian housing

Air tightness of Australian buildings is a great unknown. Despite testing methods being developed and implemented in many advanced European and North American countries, this has not happened in Australia. This paper notes energy efficiency gains that can be achieved through tighter construction, and follows on from the investigation into testing methodology and literature discussed in TEC 23: Air Leakage in Buildings – Review of International Literature and Standards. Several domestic case studies are used to implement two accepted testing methods and aid to build the case for increased awareness of airtight housing in Australia.

Ventilation research on Australian residential construction

This paper applies established testing methods used to discover the ventilation performance of various residential building envelope construction in Australia. Under the definition of 'ventilation performance' we imply the building envelope leakage (or infiltration) the living space air change rates, the volumetric flow rates and the pathways of air flow between subfloor, room volume and roof spaces. All of the methods applied and discussed here are on-site, evidencebased performance of actual structures as tested by the Mobile Architecture & Built Environment Laboratory and Air Barrier Technologies.

Ventilation research on Australian residential construction

This paper applies established and new testing methods to discover the ventilation performance of various residential building envelope constructions in Australia. Under the definition of 'ventilation performance' we imply the building envelope leakage (or infiltration) of the living space air change rates, the volumetric flow rates and the pathways of air flow between subfloor, living and roof spaces. All of the methods applied and discussed here are on-site, evidence-based performance of actual structures as tested by the Mobile Architecture and Built Environment Laboratory and Air Barrier Technologies. The testing processes primarily involve the Tracer Gas Decay Method (TGDM) and rhe fan pressurisation method (FPM a.k.a 'blower door'). All the measurements are performed with respect to the external wind speed and direction as well as the typical weather parameters. This paper discusses the differences and similarities of both testing methods as well as several other testing procedures that can inform the researcher on air leakage pathways. Findings of a simultaneous TGDM and FPM air leakage rate comparison are also encountered in this paper. One of the most informative testing methods, is the application of three different tracer gasses introduced into different spaces (subfloor, living and roof) to discover pathways of air flow within residential construction.

Experiments with stochastic processes : facade subdivision based on wind motion

Constraint based tools for architectural design exploration need to satisfy aesthetic and functional criteria as well as combine discrete and continuous modes of exploration. In this paper, we examine the possibilities for stochastic processes in design space exploration.

Specifically, we address the application of a stochastic wind motion model to the subdivision of an external building envelope into smaller discrete components. Instead of deterministic subdivision constraints, we introduce explicit uncertainty into the system of subdivision. To address these aims, we develop a model of stochastic wind motion; create a subdivision scheme that is governed by the wind model and explore a design space of a facade subdivision problem. A discrete version of the facade, composed of light strips and panels, based on the bamboo elements deformed by continuous wind motion, is developed. The results of the experiments are presented in the paper.

Strategies for improving the thermal performance and comfort levels of a kindergarten in the mountains of Nepal

Located on the Annapurna trekking trail in Nepal, Siurung is a remote mountain village where outside influences are almost non-existent. The thermal comfort levels of a recently-constructed kindergarten are well below international standards because of the climate and poor building envelope. A TRNSYS model of the kindergarten has been used to predict the current occupant comfort levels and subsequently determine the most effective way to alter the traditional construction methods to improve comfort levels. Improvements investigated were: reduced air infiltration, roof and wall insulation (separately and together), installation of a smokeless stove and a combination of all strategies.The model predicted that in the current building the PMV ranges from -1.94 in October to - 0.99 in July. It also predicted that the current PPD (%) ranges from 100 in January to 26 in July. With the combination of strategies, the predicted PMV values were all improved to between -1.08 and +0.34, and the PPD values of all months except January were reduced to below 10%. When improving the comfort levels of an existing school, reducing air infiltration, adding roof insulation and installing a smokeless stove are the most effective strategies. When constructing a new school, however, reducing air infiltration and adding insulation to the walls and roof are the most effective and feasible strategies. If a smokeless stove can be afforded and transported to the site, it is recommended that one be installed as it provides a more significant improvement than any other single strategy.

Responsive façades : parametric control of moveable tilings

The challenge of developing adaptive, responsive low-energy architecture requires new knowledge about the complex and dynamic interaction between envelope architecture, optimization between competing environmental performance metrics (light, heat and wind indices) and local climate variables. Advances in modeling the geometry of building envelopes and control technologies for adaptive buildings now permit the sophisticated evaluation of alternative envelope configurations for a set of performance criteria. 

Thermal evaluation of a greenhouse in a remote high altitude area of Nepal

Remote communities in the high altitude areas of Nepal suffer both chronic and acute malnutrition. This is due to a shortage of arable land and a harsh climate. For seven months of the year, the harvesting of fresh vegetables is almost impossible. Greenhouse technology, if appropriate for the location and its community, can extend the growing season considerably. Experience in the Ladakh region of India indicates that year-round cropping is possible in greenhouses in cold mountainous areas. A simple 50-m2 greenhouse has been constructed in Simikot, the main town of Humla, northwest Nepal. This paper describes the evaluation of the thermal performance of that greenhouse. Both measurement and simulation were used in the evaluation. Measurements during the winter of 2006-7 indicate that the existing design is capable of producing adequate growing conditions for some vegetable crops, but that improvements are required if crops like tomatoes are to be grown successfully. Options to improve the thermal performance of the greenhouse have been investigated by simulation. Improvements to the building envelope such as wall insulation, double-glazing and using a thermal screen were simulated with a validated TRNSYS model. The impact of the addition of nighttime heat from internal passive solar water collectors was also predicted. The simulations indicate that the passive solar water collectors would raise the average greenhouse air temperature by 2.5°C and the overnight air temperature would increase by 4.0°C. When used in combination, overnight temperatures are predicted to by almost 7°C higher.