F. Flourentzou

ORME : A multicriteria rating methodology for buildings

Abstract To check the compliance of a building with regulations, evaluate the efficiency of retrofit, or even label a building one would in most cases perform a comparison of a number of building qualities. Within the framework of the European Joule–Thermie OFFICE project, a multicriteria rating methodology was developed for this purpose, based on a rating method that uses principal component analysis, and a ranking method that uses a partial aggregation technique. The aim of this methodology is to rate or to rank office buildings and retrofit scenarios of the same building according to an extended list of parameters, including: • energy use for heating, cooling and other appliances, • impact on external environment, • indoor environment quality, • cost. The paper presents the principles used in the methodology, and some examples of application to actual buildings. More information is given in a complete report (ORME—Office building rating methodology for Europe, Office Project Report, University of Athens, 1999).

Natural Ventilation for Passive Cooling : Measurement of Discharge Coefficients

Abstract For the design of natural ventilation systems for passive cooling in buildings, engineers and architects are interested in the prediction of ventilation rates as a function of position and size of the ventilation openings. In common use, there are both simple and detailed (i.e., multizone) ventilation models which rely basically on the same Bernoulli algorithm to describe airflow through large openings. An important source of uncertainty is related to the attribution of discharge coefficients. The present study was undertaken to improve our knowledge on velocity and discharge coefficients when measured in real buildings. The experiments were performed on a naturally ventilated three-level office building where the staircase acted as exhaust chimney. In order to keep the flow pattern stable, a condition for air flow measurements to be reproducible, the experiments were performed on windless nights where the flow was only driven by stack pressure. Air flow patterns were traced with smoke and tracer gas. In a first set of experiments, air velocities, contraction and velocity coefficients and the position of the neutral pressure level (NPL) have been measured, in a second set of experiments, the resulting effective area of a combination of two openings in series. Air flow rates derived from velocity measurements in the open doorways were found to be in agreement with the flow rates obtained with a constant injection tracer gas technique, with an uncertainty of ± 20%. The velocity coefficient φ = 0.7±0.1 and jet contraction coefficients ɛ = 0.85±0.1 found in the experiments are shown to be in agreement with the generally accepted value of the discharge coefficient Cd = φ ɛ = 0.6±0.1, giving new justification for its use in the models. Basic configurations for ventilative cooling are given to illustrate how qualitative modeling used in simple models can give valuable information to the designer.

Elaboration of retrofit scenarios

Coherent and efficient retrofit scenarios are commonly built on the basis of the knowledge of the degradation state of the building and its obsolescence. The architect or building engineer prepares a list of refurbishment works required on the basis of the building audit, his experience and the available budget. This paper describes a systematic method, based on multicriteria analysis and a constructivist approach, which helps an expert in designing retrofit scenarios. This approach includes several steps and follows an iterative process. The associated computer tool takes charge of tedious tasks such as calculating the associated costs, performing an energy balance, and checking for coherence between actions; and presents various viewpoints to the expert. It also helps the user in quickly creating various scenarios. The expert can then interact with this information and makes the decision for selecting the final scenario. This interactive approach brings together expert intuition and rational systematic verification.

TOBUS software — an interactive decision aid tool for building retrofit studies

The TOBUS software has been developed to facilitate the implementation of the TOBUS building diagnosis and decision-making method for retrofit studies. This user-friendly software runs under the Windows® operating system and includes several modules, each of which addresses a particular aspect of the diagnosis including: building description, dimensions, cost coefficients, building diagnosis of current physical state and functional obsolescence, indoor environmental quality (IEQ), energy use, elaboration of retrofit scenarios, cost analysis, reporting results. The software also includes comprehensive databases on the physical state of degradation, including hundreds of illustrations, retrofit work details, cost, etc.

EPIQR-TOBUS: a new generation of refurbishment decision aid methods

In a large majority of European countries, maintenance and refurbishment work represents nearly 50% of the total amount spent in the building sector. New requirements are being added to the necessity of maintaining or re-establishing the building stock’s usage value. They are linked to a move to reduce energy consumption, pollutant emissions and work site wastes, and to improve the Indoor Environment Quality (IEQ) and all the modern conveniences inside buildings.

Design and performance of controlled natural ventilation in school gymnasiums

ABSTRACT For zero and low energy buildings, high-energy efficiency ventilation is very often confused with a complex mechanical ventilation system with heat recovery. In school gymnasiums, where large volumes have to be ventilated, and where intermittent occupation is very usual, demand-controlled natural ventilation has several advantages, making this technique attractive. High stack height makes natural ventilation very efficient. Natural ventilation is attractive for architects because of no ducts, no apparent mechanical components and low-cost. The article shows the design concept of controlled natural ventilation for a high-energy performance school gymnasium (Minergie® labeled), situated in Saviese-Switzerland. Several months of monitoring shows the high level of comfort and air quality, that controlled natural ventilation provides in this type of buildings, during winter and summer. Simulations, comparing the purely naturally ventilated hall with a fully mechanical system and a hybrid one, show the energy performance of the different ventilation systems. A life cycle assessment shows that controlled natural ventilation has comparable and even better performances than a heat recovery system.