VRF systems are touted for their superior part-load performance compared to conventional HVAC systems. This study compares both the full and part-load performance of a VRF system with a conventional RTU VAV (rooftop variable air volume) system in a multi-zone office building with emulated occupancy. During the study period starting July 2015 through February 2016, each system was operated alternately under each of the three load conditions for 2-3 days, and the system parameters, indoor and outdoor conditions, loads, and energy use were monitored. The performance of the two systems is compared in terms of weather-normalized HVAC energy consumption.

Water-based air conditioning system has attracted increasing attention because of their smaller charge amount of refrigerant which is supposed to cause global warming. It is widely used for such as chiller, and there are more requirements for higher efficiency and improvements in workability in building use. This paper discusses the outline of HVRF and explains the refrigerant and water flow. HVRF enables free selection of a cooling mode or a heating mode in each indoor unit. It also discusses the coupled simulation of refrigerant circuit and water circuit.

Europe, with a building stock responsible for about 40% of the total energy use, needs to reduce the primary energy consumption in buildings in order to meet the 2020 energy targets of the European Union. High temperature cooling and low temperature heating systems, and as an example, Thermally Activated Building Systems (TABS), have proven to be an energy-efficient solution to provide buildings with an optimal indoor thermal environment. This study focuses on quantifying the impact of two types of free hanging ceiling absorbers (horizontal and vertical), on the cooling performance of the TABS and the implications this has on the occupants´ thermal comfort.

This paper presents a first-order physics based model which reasonably accounts for the fundamental heat and mass transfer of vapor from humid air feed side to permeate side. This model comprises two membrane mass transfer submodels (i.e. microstructure model and performance map model); moreover, we adopt a segment-by-segment methodology for discretizing heat and mass transfer governing equations. The reported model is capable of simulating both dehumidifiers and energy recovery ventilators with cross-flow, counter-flow and parallel-flow. The model has been validated with measurements of a working device.