• Energy Research

A growing focus on occupant comfort, health and wellbeing has resulted in attempts to quantify indoor environmental quality (IEQ) and to determine the relative contributions of single IEQ aspects to an overall IEQ index. The recently developed IV20 tool assesses potential IEQ to label overall IEQ, and assign separate scores for the main indoor environment (IE) areas: thermal, visual, acoustic and air quality. In the absence of objective, universally applicable IEQ weights, this paper develops and executes a methodology asking regional experts with different backgrounds to make relative comparisons between related IE aspects. The authors hypothesize that wide-ranging subjective evaluations can be combined into useful relative weights (best operational solution based on the current status of IE literature). This paper presents results from an IE expert survey on relative IE aspect weights using simple percentile prioritization and the Analytic Hierarchy Process pairwise comparison. Results are compared to expert panel judgements to ensure validity. The advantages of this combined weight determination method are (1) that the expert survey ensures a broad spectrum of opinions and allows for input from different built environment disciplines, and (2) that the expert panel has tool-specific insight, methodology awareness and state of the art knowledge.

Abstract The share of the energy use for domestic hot water (DHW) in the total energy consumption of buildings is becoming more and more prominent. Depending on the building typology it varies between 20% to 50% of the total energy usage for old and new built single family house, respectively. The aim of this paper is to determine the energy losses in the DHW installation with division between: a) loss at the production point, b) loss in the distribution, and c) loss at the draw-off points using the results of the measurements of DHW consumption in two single family houses connected to district heating grid. The total Eloss for the two houses vary between 17% and 26%. For House 1, the production loss accounts for 8%, the pipe loss for 15% and loss at the draw off points for 3%. Moreover, the results shown that the layout of the house, in particular the placement of the bathrooms with showers or bath tubs has significant impact on the size of the distribution losses.

There is very little knowledge on the occupant actual hot water comfort (temperature and flow), usage practice, and routines (temporal and spatial distribution of hot water usage in a household). This paper describes the results from the total and hot water measurements in two Danish detached houses. The results show that, at the draw-off points, the temperature of 55 °C is never asked by the occupants, not even in the kitchen sink. The domestic water temperature differentiates depending on the function of the draw-off point, with the shower and kitchen taps being most energy- and water-intense. They constitute around 90% of the hot water use in the house. Shower units on average demand for highest temperature (i.e., 35.5 °C to 40.4 °C). Hand washing operates, on average, at temperature between 20.5 °C to 26.5 °C. Average water temperature at the taps located in utility room varies between 23 °C to 26 °C. These in-depth insight in the total and hot water use in two new-built low energy houses, can a) help building professionals designing more efficient hot water installations; b) enhance the research work on energy flexibility buildings by providing knowledge on most energy-intensive draw-off points; and c) facilitate district heating professionals in improving the network performance.

Research and practice agree that decisions taken early in a project have a higher impact and are less costly. Current building performance assessment methods are not suited to accommodate the responsiveness required for early design processes and are often used for validation in the later stages where the feedback has little design impact. Tools developed specifically for early-stage Design Decision Support (DDS) are either too simplistic, provide no solution to addressing combined indoor environmental quality (IEQ), or risk worsening the overall IEQ by optimizing performance indicators in isolation. Most comprehensive building assessment methods evaluate several topics but follow a linear approach which fails to support holistic performance feedback and fails to meet the demand for assessment speed. This paper presents application examples of a holistic IEQ assessment tool (IEQCompass) in design processes. Design experiments demonstrate that the applied approach can meet the challenges of early-stage DDS pointed out in existing literature. Findings from the experiments indicate that the IEQCompass can provide: (1) seamless early-stage assessments through rapid-feedback on changing designs, (2) timely decision support by guiding design teams with criteria overviews, design comparisons and holistic assessment results and (3) dialogue and communication support between architects, engineers and clients.

Much effort has been put in tightening the building regulations. Though, the energy usage for domestic hot water stayed unchanged constituting a bigger share of the energy pie over the years. Due to the cost, timeframe, and workload associated with instrumentation and installation, the vast majority of the DHW measurements are limited to the household level. This paper introduces a high resolution measuring technique for DHW consumption and its application in a single family house. By applying this technique, we are able to measure the duration, flow and temperature of each water draw event in the house and thus create both the temporal and spatial DHW consumption profiles. The results indicated that the duration of draws varies significantly between tapping places, i.e. the draws in the shower and in the kitchen have an average duration of 300 sec. and 20 sec., respectively. The high resolution metering system was able to record the inefficient use of DHW, at periods when the water temperature was not meeting the users’ requirements, e.g. the wasted energy at the shower depending on the usage patter varies between 25% and 42%. The measured temperature range of DHW in the household is between 52°C (kitchen) and 21°C (sink in utility room).

The study in this article investigates 15 ventilated window typologies with different pane configurations and glazing types in climates of four European countries (United Kingdom, Denmark, France and Germany) in order to identify the optimum typology with regard to their energy balance and impact on thermal comfort. Hourly simulations of the heat balances of the windows are conducted on four days representing different typical weather conditions according to the method described in EN ISO 13790. U and g values used in the calculation method are calculated in European software tool (WIS) for the calculation of the thermal and solar properties of commercial and innovative window systems. Additionally, comfort performance is evaluated by inlet air temperature and internal surface temperature of the windows calculated by WIS software.The results of the study show the energy and comfort performance of different ventilated window typologies and provide optimally ventilated window typologies for climates of these four European climates. The typologies with solar control or Low-emissivity (Low-e) coatings and typologies with double glazing on the outside have better performance in terms of either minimizing the energy consumption or optimizing the thermal comfort. The provided optimal window typologies can be used in residential and commercial buildings for both new constructions and renovations. The use of solar shading in future low energy office buildings is essential for minimizing energy consumption for building services, while maintaining thermal conditions. Implementing solar shading technologies in energy calculations and thermal building simulation programs is essential in order to demonstrate the effect of adaptive solar shading. Much literature covers the detailed description of solar shading in correlation with the glazing system. However in order to document the benefits of the shading technology, the description of the shading device in the thermal building simulation software must be described at a reasonably accurate level, related to the specific solar shading device. This research presents different approaches for modeling solar shading devices, demonstrating the level of accuracy in relation to full-scale measurements conducted at Aalborg University. Modeling of solar shading bridges the gap between increased complexity of solar shading technologies and the use of these technologies in thermal building simulation software.

Studying the thermal performance of Double Skin Facades (DSFs) with vertical layers has dominated the literature,however, there is still a lack of in-depth research on the performance of DSFs with atypical geometries suchas folded cases which can be applied to Building Integrated Photovoltaic (BIPV) systems to improve their performance.To this end, the study evaluates the influence of the fold geometry on heat transfer, flow structure, andairflow rate in the Folded DSF cavities under a hot climate in Iran using an efficient method titled “patching”; themethod integrates Soltrace3 with a 2D steady-state CFD model by ANSYS-Fluent. The results show that the foldposition and its depth can alter the DSFs performance significantly; the higher the fold depth the more distortionof the flow field inside the cavity; from a practical perspective, the fold position in the upper part of the cavity issuitable for BIPVs application since it can capture 250% higher amount of solar radiation compared to a conventionalvertical-layer DSF as the Base Case; the net heat gain through outer layer could improve with increaseof fold depth and reach at least 33% higher than the Base Case, meanwhile, the total electricity generationpotential of folded cases could be up to 169% higher than the Base Case; thus, the study proved that if thearchitectural design is of interest, it is highly recommended to consider folded DSFs as a design option.

Artificial lighting represents 15-30% of the total electricity consumption in buildings in Scandinavia. It is possible to avoid a large share of electricity use for lighting by application of daylight control systems for artificial lighting. Existing methodology for estimation of electricity consumption with application of such control systems in Norway is based on Norwegian standard NS 3031:2014 and can only provide results from a rough estimate. This paper aims to introduce a new estimation methodology for the electricity usage with the daylight- and occupancy-controlled artificial lighting in an office, which is both accurate and rapid. The method is validated for an office building in Oslo, Norway, using the experimentally obtained data and the data from the Building Management System.