Energy saving potential of a two-pipe system for simultaneous heating and cooling of office buildings

TitleEnergy saving potential of a two-pipe system for simultaneous heating and cooling of office buildings
Publication TypeJournal Article
Year of Publication2017
AuthorsMaccarini, Alessandro, Michael Wetter, Alireza Afshari, Goran Hultmark, Niels Bergsoe, and Anders Vorre
JournalEnergy and Buildings
Volume134
Pagination234 - 247
Date Published01/2017
ISSN03787788
Keywordsactive beams, energy saving, HVAC systems, low-exergy, modelica, simulation
Abstract

This paper analyzes the performance of a novel two-pipe system that operates one water loop to
simultaneously provide space heating and cooling with a water supply temperature of around 22°C.
To analyze the energy performance of the system, a simulation-based research was conducted. The
two-pipe system was modelled using the equation-based Modelica modeling language in Dymola.
A typical office building model was considered as the case study. Simulations were run for two
construction sets of the building envelope and two conditions related to inter-zone air flows. To
calculate energy savings, a conventional four-pipe system was modelled and used for comparison.
The conventional system presented two separated water loops for heating and cooling with supply
temperatures of 45°C and 14°C, respectively. Simulation results showed that the two-pipe system
was able to use less energy than the four-pipe system thanks to three effects: useful heat transfer
from warm to cold zones, higher free cooling potential and higher efficiency of the heat pump. In
particular, the two-pipe system used approximately between 12% and 18% less total annual primary
energy than the four-pipe system, depending on the simulation case considered.

DOI10.1016/j.enbuild.2016.10.051
Short TitleEnergy and Buildings