The objective of this document is to promote the use of dynamic daylight performance measures for sustainable building design. The paper initially explores the shortcomings of conventional, static daylight performance metrics which concentrate on individual sky conditions, such as the common daylight factor. It then provides a review of previously suggested dynamic daylight performance metrics, discussing the capability of these metrics to lead to superior daylighting designs and their accessibility to nonsimulation experts. Several example offices are examined to demonstrate the benefit of basing design decisions on dynamic performance metrics as opposed to the daylight factor.

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Dynamic Daylight Performance Metrics for Sustainable Building Design

Useful daylight illuminances: A replacement for daylight factors

The drive towards sustainable, low-energy buildings has increased the need for simple, yet accurate methods to evaluate whether a daylit building meets minimum standards for energy and human comfort performance. Current metrics do not account for the temporal and spatial aspects of daylight, nor of occupants comfort or interventions. This paper reviews the historical basis of current compliance methods for achieving daylit buildings, proposes a technical basis for development of better metrics, and provides two case study examples to stimulate dialogue on how metrics can be applied in a practical, real-world context.

/pdf/daylight-metrics-and-energy-savings-yftotkg2fw.pdf

Daylight metrics and energy savings

This paper presents a vision of how state-of-the-art computer-based analysis techniques can be effectively used during the design of daylit spaces. Following a review of recent advances in dynamic daylight computation capabilities, climate-based daylighting metrics, occupant behavior and glare analysis, a fully integrated design analysis method is introduced that simultaneously considers annual daylight availability, visual comfort and energy use: Annual daylight glare probability profiles are combined with an occupant behavior model in order to determine annual shading profiles and visual comfort conditions throughout a space. The shading profiles are then used to calculate daylight autonomy plots, energy loads, operational energy costs and green house gas emissions. The paper then shows how simulation results for a sidelit space can be visually presented to simulation non-experts using the concept of a ‘daylighting dashboard’. The paper ends with a discussion of how the daylighting dashboard could be practically implemented using technologies that are available today.

The daylighting dashboard - a simulation-based design analysis for daylit spaces

The daylighting dashboard – A simulation-based design analysis for daylit spaces

This paper introduces a new paradigm to assess daylight in buildings called ‘useful daylight illuminance’, or UDI. The UDI paradigm preserves much of the interpretive simplicity of the conventional...

Useful daylight illuminance: a new paradigm for assessing daylight in buildings:

This paper describes a methodology to compare the energy benefit that may result from the adoption of two very dfferent facade technologies in non-domestic buildings. A comparison is made of the energy benefit that might result from: (a) replacing conventional glass with electrochromic
glazing; and, (b) installing PV panels across the opaque sections of vertical facade. The energy benefit from electrochromic glazing is predicted on
the basis of displaced electric lighting usage against standard glazing with
blinds, whereas the energy benefit from facade PV panels is equal to their
delivered electrical output. The evaluation setting is a 'typical' six metre
deep perimeter office space with vertical glazing. Office orientations for each
of the four cardinal compass points are considered. Performance evaluations
are founded on a full year's hourly meteorological data for fourteen locales
across the world. The predicted energy benefit from electrochromic glazing
and facade PV are related to the total annual vertical irradiation incident on the building facade. The findings indicate that the energy benefit that results
from replacing standard glazing with electrochromic glazing may exceed that
of facade PV for the majority of cases studied. Surprisingly, electrochromic
glazings are found to provide the greatest energy benefit for those cases at
the lower end of the experienced range in total annual vertical irradiation.
The effectiveness of widespread deployment across multiple facades for each
locale is examined. The likelihood that electrochromic glazing alone can offer
sufficient solar protection without recourse to additional shading is assessed
using the recently formulated useful daylight illuminance scheme.

/pdf/electrochromic-glazing-and-facade-photovoltaic-panels-a-6yw6u6pfbc.pdf

A. Nabil

Papers

Useful daylight illuminance: a new paradigm for assessing daylight in buildings:

Electrochromic glazing and facade photovoltaic panels: a strategic assessment of the potential energy benefits