Simplified Space-heating Distribution In Highly Insulated Apartment Buildings

Many of the building concepts for current and future energy-efficient buildings are based on highly-insulated building envelopes,such passive houses(PH),zero emission buildings or nearly-zero energy buildings(nZEB).As the building is highly insulated,it is possible to simplify the space-heating(SH)distribution subsystem and reduce the number of heat emitters to a few elements.One solution is to use a hydronic distribution equipped with few low-temperature radiators,for instance,one in each floor as well as one floor heater in the bathroom.This solution reduces thermal losses from the pipes and the investment,but theoretically provides for less thermal comfort than a complete standard loop.For this purpose,four 2-weeks measurements are done in two apartments which accord to Norwegian PH standard.It turns out that the average temperature difference between hallway and bedroom1 is roughly 4.5?(Apartment 1)and 5.5?(Apartment 2),while hallway is warmer one.Largest temperature stratification phenomenon occurs in hallway,where the radiator is,roughly 1.5?,which means the thermal comfort is appreciatedMeanwhile,interviews of resident are investigated.Even though there is no heat emitter in bedroom,that bedroom is too warm for both residents from these two apartments,which is not as most people expect.Based on the results of measurement and interview,detailed dynamic simulation model(here IDA-ICE)is made and calibrated.Then,several simulation cases are done in order to find the relationship among heat demand for SH,indoor temperature,and some variables,such as state of the door/window,internal gains,temperature set-point of radiator/supply air,efficiency of heat recovery unit(HRU)and etc.In terms of temperature set-point schedule of the radiator,21?,19/21? and 18? cases do not have very noticeable difference for the yearly energy consumption of radiator.On the contrary,when temperature set-point is up to 24?,the value of energy efficiency is 60% of base case(21?).Among all the control strategies tested,control 2b is the best.That is changing the set-point of the heating battery(Tset,AH)and heat recovery(Tset,HR)to 16? and opening the window when bedroom1 temperature is higher than 16?.In that case,over 90% time of at night during heating season,temperature in bedroom is between 16? and 18?,no matter the set-point of the radiator is 21? or 24?.