Paper Conference

Proceedings of eSim 2012: 7th Conference of IBPSA-Canada


Assessing Qualitative Criteria in the Design of Cost-Optimal, Cold-Climate, Net-Zero Energy Homes

Mark Carver, Jeff Blake, P. Eng, Gary Proskiw

Abstract: This paper presents a methodology for assessing qualitative aspects and addressing barriers to implementing energy conservation measures and renewable energy technologies in optimizing the design of net-zero energy homes (NZEH). Recent demonstration projects have proven that net-zero or near-zero energy homes are technically feasible in Canadian climates. However, projects to date have used custom-engineered, complicated, and sometimes unreliable advanced energy systems that occupants do not understand and contractors often can not support. Furthermore, the incremental costs to build these homes have ranged from $90-120k or more above the cost to build a conventional home. A study seeking to reduce first costs to build NZE homes by developing a framework to apply optimization to the design process has been carried out. This paper focuses on the development and application of a “soft optimization” process to ensure cost-optimal design solutions are highly constructible and compatible with consumer expectations. Building on a best-practice review study including interviews with designers of existing NZE homes, the authors convened an Industry Advisory Committee to identify the necessary qualitative design criteria for consideration in addition to cost and energy performance. Industry needs identified through this work include: system simplicity; durability; minimized occupant impact; sufficient industry capacity to install and support; and minimized uncertainty. The quantitative performance of various technologies is assessed by determining the specific cost to conserve or produce a unit of secondary energy ($/kWh). The “soft-optimization” methodology follows a pseudo-design process similar to that used in the design of many low-energy homes. For each energy-related building component, various efficiency measures are applied to a base 225m2, single, detached archetype house. These are modelled using HOT2000 and contrasted in terms of their installed first cost to conserve a unit of energy. Simultaneously, the qualitative criteria are assessed for each technology. Using a scoring matrix, the most cost-effective technologies that meet each of the qualitative criteria are selected. Using the technology pathways defined through “softoptimization,” an initial specification set for achieving NZE performance will be defined for the archetype house. “Fine-optimization” will be carried out using ESP-r for energy performance simulation, and GenOpt optimization software to determine the lowest first cost at which NZE performance is achieved.
Pages: 215 - 229