Thermal zoning and interzonal airflow in the design and simulation of solar houses: A sensitivity analysis

Many assumptions must be made about thermal zoning and interzonal airflow for modelling the performance of buildings. This is particularly important for solar homes, which are subjected to high levels of periodic solar heat gains in certain zones. The way in which these passive solar heat gains are distributed to other zones of a building has a significant effect on predicted energy performance, thermal comfort and optimal design selection. This article presents a comprehensive sensitivity analysis that quantifies the effect of thermal zoning and interzonal airflow on building performance, optimal south-facing glazing area, and thermal comfort. The effect of controlled shades to control unwanted solar gains is also explored. Results show that passive solar buildings, in particular, can benefit from increased air circulation with a forced air system because it allows solar gains to be redistributed and thus reduces direct gain zone overheating and total energy consumption

The development of a solar house design tool

Building designers need design tools that enable them to rapidly explore the energy performance implication of early design decisions. The tools should enable them to use their experience, along with performance feedback, to find near-optimal solutions, according to their criteria. This paper presents a methodology for a solar house design, followed by a description of how it will be implemented in a design tool. The design tool will use three methods to aid the designer, including: a reduction of the number of parameters, decomposition of certain subsystems, and instantaneous performance feedback. The focus of the paper is on some of the fundamental design issues. Two innovative means for feedback are presented. The final part of the paper explains the computational feasibility of providing the feedback in real-time

Parametric analysis to support the integrated design and performance modeling of net zero energy houses

Building performance models routinely involve tens or hundreds of components or aspects and at least as many parameters to describe them. This results in overwhelming complexity and a tedious process if the designer attempts to perform parametric analysis in an attempt to optimize the design. Traditionally, during design, parameters are selected on a one-at-a-time basis and, occasionally, formal mathematical optimization is applied. However, many subsets of parameters show some level of interaction, to varying degrees, suggesting that the designer should consider manipulating multiple design parameters simultaneously. This paper is divided into two parts. The first part presents a methodology for identifying the critical parameters and two-way parameter interactions. The second part uses these results to identify the appropriate level of modeling resolution. The methodology is applied to a generic model for net-zero or near-net-zero energy houses, which will be used for an early stage design tool. The results show that performance is particularly sensitive to internal gains, window sizes, and temperature setpoints, and they indicate the points at which adding insulation to various surfaces has minimal impact on performance. The most significant parameter interactions are those between major geometrical parameters and operating conditions. Increased modeling resolution for infiltration and building-integrated photovoltaics (BIPV) only provides a modest improvement to simpler models. However, explicit modeling of windows, rather than grouping them into an equivalent area, has a significant impact on predicted performance. This suggests that identifying and implementing the appropriate level of modeling resolution is necessary, and that it should be detailed for some aspects even in the early stage design

Solar design days: A tool for passive solar house design

Passive solar heating of homes is a dynamic process for which solar energy is transmitted through glazing and then absorbed by the interior building components and released to the indoor air over time. This paper presents solar design days as a useful method for understanding passive solar buildings' dynamic behavior for the purpose of increasing energy performance and thermal comfort through interactive design at the conceptual design stage. Rather than relying on rules of thumb or assessing whole-year performance from building energy simulations to optimize passive solar measures, solar design days can be used to compare different design options by diagnosing potential problems such as excessive heat loss, peak loads, and overheating. Solar design days consist of representative cold sunny, cold cloudy, warm sunny, and mild sunny days. This paper provides a background on recent advances in passive solar design, a methodology for selecting and applying solar design days, a modeling approach for passive solar houses in EnergyPlus, and finally, an example

Development and visualization of time-based building energy performance metrics

In the face of climate change, and as building codes and standards evolve to promote increased building energy efficiency and reduced carbon footprints, it is also important to ensure that buildings, especially housing, can withstand prolonged power outages during extended periods of both extreme cold and hot weather to provide habitable shelter passively. This paper examines an approach for visualizing the impact of robust passive measures in multi-unit residential buildings by examining the ‘weakest links in the chain’ – the suites most susceptible to underperforming – in three climatic zones: Toronto and Vancouver, Canada; and Adana, Turkey. Two time-based and thermal comfort-related metrics are explored: thermal autonomy, a measure of what fraction of the time a building can deliver comfort without supplemental active systems; and passive survivability (also termed thermal resilience), a measure of the length of time a building remains habitable following the onset of a prolonged power outage during a period of extended extreme weather. A visualization of the results of parametric building energy simulations helps guide the selection of passive architectural parameters at the early stages of design to promote enhanced environmental performance and resilience