Domestic Hot Water Profiles for Energy Calculation in Finnish Residential Buildings Kaiser Ahmed 1, *, Petri Pylsy 1, 3 , Jarek Kurnitski 1, 2 1 Aalto University, Department of Civil and Structural Engineering, Finland 2 Tallinn University of Technology, Faculty of Civil Engineering, Estonia 3 The Finnish Real Estate Federation, Finland *corresponding author: Rakentajanaukio 4 A, FI-02150 Espoo, Finland; E-mail: kaiser.ahmed@aalto.fi ____________________________________________________________________________________________________ ABSTRACT The information of domestic hot water (DHW) consumption is important to identify the delivered energy for building sector. Daily basis hourly profile, daily profile, weekday and weekend profile, monthly profile might be helpful to optimize the required DHW consumption which further useful document for energy optimization and system designer. This paper has shown the investigated result of 182 Finnish residential apartments and draws a monthly, weekdays and weekend basis DHW profile. The finding also correlated with some factors such as occupant number, seasonal variation, behavioral approach, weather condition. The average consumption for January to December is noted 47 liter/person/day which are also varied based on monthly, weekdays and weekends weighted average factor. Higher consumption of DWH is observed during November to February whereas opposite behavior is observed during May to July. In addition, the hourly profiles for weekdays and weekend are different and DHW consumption is higher during weekdays. Most frequent DHW consumption is observed from 20 to 60 (L/person/day) and the ratio of hot to cold water is varied from 0.3 to 0.5. The obtained profiles will give an idea about the scenario of DHW consumption during the different months as well as variances of weekday and weekend. KEYWORDS Residential building; DHW; Monthly factor; Weekdays and weekend factor Abbreviation DHW, Domestic Hot Water RE, Renewable Energy WD, Week Day WE, Weekend SD, Standard Deviation ____________________________________________________________________________________________________ 1. INTRODUCTION The building sector has consumed around 40% of world’s energy (IEA, 2008) whereas a large percentage of it has used for domestic hot water. Among this consumption, residential building shows significantly high percentage of consumption compare to small scale business users and large scale business users (Geudens, 2008). The complexity of DHW has an involvement with user spectrums, local weather condition, energy cost, occupant density, end user behavior, local culture, etc. Other important parameters such as modern life style, vacation period, shower time, hygiene sense, and comfort life style might be added more DHW consumption. That might be the reason of higher fluctuation of DHW consumption. Sometimes it might be difficult to find out the reason behind the higher fluctuation due to occupant’s behavior, occupant density due to privacy problem etc. Thus, some previous works have used the local statistical report on the occupant density, occupant type to predict the actual consumption. Occupancy is the key indicator of consumption (Parker, 2003) which means that higher density increases the gross consumption. Merrigan (1988) has discussed the relation between occupant number and consumption rate which is nearly linear. He also added 45 l/d for each additional person where the occupant number is above 2. Many studies also found higher fluctuation as well as different consumption rate of DHW. Wiehagen and Sikora (2002a) found the average DHW consumption was 236 l/d of 59 residences in Canada whereas per capita use was varied from 47 l/d to 86 l/d. Another North American study summarized the average consumption is 239 l/day which had a consideration of seasonal variation, ownership, occupant ages (Becker & Stogsdill, 1990). VTT drew a conclusion of 6 Finnish households DHW consumption and found an average consumption is 135 l/day for every household and 43 l/day for individual occupant (IEA, 2007).