Net ZEB Design Processes and Tools - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 230

performance, unlike most types of buildings. This means that tools must
be able to predict whether a building can achieve net-zero energy both
in accurate and certain terms. This requires more accurate and realistic
mathematical models for virtually all aspects of buildings (materials,
construction quality), occupant-building interactions, and current and
future climate scenarios.
2. Need for models for advanced technologies. The ambitious objective of
net-zero energy often requires a combination of established
technologies and design concepts with state-of-the-art technologies and
controls. Currently, there is a lag time between building system
development and the corresponding BPS models. This presents a
barrier to building designers who want to confidently demonstrate that
a building with advanced technologies will achieve predicted
performance.
Several extensive reviews for the needs of future tools and features can
be found in the literature (Attia et al. , 2009; Augenbroe, 2002; Ellis and
Mathews, 2002). Furthermore, a survey was conducted about the strengths
and shortcomings of existing simulation tools in the context of Net ZEBs
among the experts of IEA SHC Task 40/EBC Annex 52. Key results of the
aforementioned studies are provided here:
- Ease of use: Net ZEB tools must be easy to use so that they appeal to a
wider range of designers. This means intuitive user interfaces,
transparency (e.g., no hidden features or assumptions), standard user
interface features (e.g., undo and auto-save), minimal redundant
inputs, efficient input methods, and comprehensible outputs.
- Accuracy: Net ZEB design tools need to be accurate in order to help
designers predict net-zero energy with a high level of certainty. While
early stage design tools can afford some inaccuracy since they provide
rapid feedback and focus on relative performance, tools used for
detailed design must be accurate. Accuracy extends beyond the
numerical methods representing heat transfer and other physical
phenomena to having reasonable built-in assumptions and default
values (e.g., for occupants, weather conditions, and plug loads).
- Availability of building features and technologies: Net ZEBs tend to
involve technologically advanced building features in order to achieve
this aggressive energy target. As discussed in Chapter 7 , many of the