TY - JOUR
T1 - High frequency flow and temperature measurements of domestic water in two office and education buildings
AU - Frandsen, Martin
AU - Vind Madsen, Jakob
AU - Lund Jensen, Rasmus
AU - Zbigniew Pomianowski, Michal
N1 - Publisher Copyright:
© 2022 The Author(s)
PY - 2022/11/1
Y1 - 2022/11/1
N2 - For a long period, the energy use for domestic hot water (DHW) in non-residential buildings has been neglected. As energy use for space heating, ventilation, and lightning has been reduced through the years, the energy share for DHW production has increased. With today's focus on energy efficient buildings, the DHW systems must not be left behind the other fields to obtain a holistic approach to energy efficient buildings. To develop more energy efficient DHW systems for non-residential buildings, more knowledge is needed regarding draw-off durations, flow rates, and water temperatures from different draw-off types. This paper presents high frequency measurement results in two Danish office and educational buildings, which show that three DHW systems only utilize between 3.4 and 7.5 % of the total energy used for DHW production. Above 85 % of the total energy use is lost from the recirculation circuit to secure a high hot water temperature at the draw-off point. However, temperature measurements at the draw-off points show that a significant share of the heat is lost from pipes not covered by recirculation. One reason is draw-off durations are approximately 50 % of the time below 10 s at washbasins and kitchen sinks. Another reason is actual maximum flow rates are far from the calculated design flow. The high frequency measurements at multiple draw-off points give essential knowledge of use patterns for washbasins, kitchen sinks, and service sinks in non-residential buildings. This knowledge can contribute to developing energy efficient DHW systems and new types of DHW production.
AB - For a long period, the energy use for domestic hot water (DHW) in non-residential buildings has been neglected. As energy use for space heating, ventilation, and lightning has been reduced through the years, the energy share for DHW production has increased. With today's focus on energy efficient buildings, the DHW systems must not be left behind the other fields to obtain a holistic approach to energy efficient buildings. To develop more energy efficient DHW systems for non-residential buildings, more knowledge is needed regarding draw-off durations, flow rates, and water temperatures from different draw-off types. This paper presents high frequency measurement results in two Danish office and educational buildings, which show that three DHW systems only utilize between 3.4 and 7.5 % of the total energy used for DHW production. Above 85 % of the total energy use is lost from the recirculation circuit to secure a high hot water temperature at the draw-off point. However, temperature measurements at the draw-off points show that a significant share of the heat is lost from pipes not covered by recirculation. One reason is draw-off durations are approximately 50 % of the time below 10 s at washbasins and kitchen sinks. Another reason is actual maximum flow rates are far from the calculated design flow. The high frequency measurements at multiple draw-off points give essential knowledge of use patterns for washbasins, kitchen sinks, and service sinks in non-residential buildings. This knowledge can contribute to developing energy efficient DHW systems and new types of DHW production.
KW - DHW energy efficiency
KW - DHW recirculation system
KW - Domestic cold water, DCW
KW - Domestic hot water, DHW
KW - Domestic water flow rate
KW - Measuring campaign
KW - Water draw-off profile
KW - Varmt brugsvand
KW - Varmt brugsvand cirkulation
KW - Brugsvand
KW - Vandtemperatur
KW - Volumenstrøm
UR - http://www.scopus.com/inward/record.url?scp=85137163115&partnerID=8YFLogxK
U2 - 10.1016/j.enbuild.2022.112424
DO - 10.1016/j.enbuild.2022.112424
M3 - Journal article
AN - SCOPUS:85137163115
SN - 0378-7788
VL - 274
JO - Energy and Buildings
JF - Energy and Buildings
M1 - 112424
ER -