2016 ASHRAE Annual Conference

This paper presents the energy efficiency, cost effectiveness and development potential of a new energy supply concept. The concept is based on solar hybrid, bore hole heat storage and a ground source heat pump. The back of the photovoltaic cells is cooled with cold water to increase the efficiency. The heated water is then connected to the cold side of a ground-source heat pump (GSHP) and to bore holes. The heat from the solar hybrid can be used in several ways to increase the efficiency of the heat pump, e.g. as the direct source of heat or to recharge the bore holes. A housing association consistent of 70 terraced houses on the west coast of Sweden has installed this new system solution. The system consists of 337 m²solar hybrid panels mounted on the roof of the terraced houses, and GSHP with seven bore holes. During the year of 2015 detailed measurements on this full scaled system is performed. In this paper presents the results from these measurements, as well as analysis of the data. The analysis aims to quantify the energy efficiency of the system. The first results show that the system has a good efficiency and that the energy demand has decreased significantly. The monitoring has also been used as a tool to adjust the system and optimize the system solution. After only a few months of monitoring adjustments advices for improvements of the regulation strategies were suggested and implemented. These changes have led to a system that is now even more efficient than at the initial installation. In parallel to the monitoring the experiences from the housing association is investigated through interviews and enquiries. In the paper their perception of common ownership, obstacles in the implementation and advices on procurement will be presented. The paper aims to increase the knowledge about this system solution with solar hybrid and geothermal combined. The increased knowledge will eventually lead to a broader implementation of this system solution with 100 % renewables.

In Canada, outside air temperatures can vary significantly during the year. A temperature gradient of 70 ⁰C between the cooling and heating season is common in many regions. Because of the high thermal inertia of the soil, airflow circulating in earth tubes will benefit of  a significant temperature increase or decrease with respect to heating or cooling season . The advantages of an earth-to-air heat exchange system are its simplicity, high pre-cooling and pre-heating potential leading to fossil fuel savings and related emisssions and low operation maintenance costs. Very few experimental studies of ground temperature impact on heating with earth-to-air heat exchanger were found in the literature for cold climate. This paper deals with the performance of an earth-to-air heat exchange system for an operational Canadian building, with the aim of characterizing its efficiency. The building, called Earth Rangers, is a visitors’ centre built to educate children about biodiversity, conservation and the adoption of more sustainable behaviors. The earth tube system is an earth-to-air heat exchanger system which consists of nine 900 mm diameter, 20 m long pre-cast concrete pipes buried beneath the frost line (approximately 1500 mm below grade). Outside air is drawn through the buried concrete pipes allowing surrounding earth to moderate the temperature of the incoming air so that it is either pre-heated or pre-cooled depending on the time of year. The performance assessment of the earth tube system consisted of continuous monitoring between January and November 2014.Results from winter and summer field monitoring are presented in terms of overall heat exchanger effectiveness and comparing the pre-heating effectiveness of the  monitored earth tubes and exploring what could be done to improve the design. This long-term field study on earth tubes has confirmed the overall effectiveness of this passive means during the winter and summer conditions.

At the technical University of Denmark, research in energy balance in buildings in relation to indoor climate has been performed with good results for decades. During the last 2 decades, research in the field of Integrated Energy Design (IED) focusing on the earliest design phases has played a major role. Research demonstrate that the largest effect in relation achieving net zero energy buildings is obtained when indoor climate and energy simulation tools are applied from the first architectural sketches, where geometry, façade design  and orientation etc.  is determined. Large architectural offices and engineering consultancies in the region have invested in software and interdisciplinary design teams and perform Integrated Energy Design (IED). Legislation has been altered; Simulations of indoor climate and energy balance is required in order to obtain building permits. IED has been rolled out extensively in the building industry. Having reduced the energy needed to operate the indoor environment to almost zero, by designing with knowledge and optimizing systems, the energy needed to construct the building and its systems comes forth as important.  The CO2 impact of buildings becomes an important parameter because sustainability certification systems like Deutche Gesellschaft für Nachhaltiges Bauen (DGNB) has taken a lead in Europe. The DGNB system includes Life Cycle Assesment (LCA) and Danish government has stated that Denmark must be CO2 neutral by 2050. The focus shifts from energy and indoor climate to CO2 impact in relation to design. The experience from the decades of IED manifests, that the largest gain in reduction stems from the early design phases. LCA in relation to buildings has to include the energy needed to operate the buildings indoor climate as well as embodied CO2 in the building.  This makes the simulations far more complex. LCA thus tends to be placed in the last design phases and used for evaluation: only a single iteration is needed. However real-time LCA simulation tools are required, if designers are to base design decisions on not only knowledge concerning indoor climate and energy balance but also LCA. The paper presents the efforts at DTU, Department of civil engineering, to develop  real-time LCA simulation tools including indoor climate and energy balance simulation (based on Energy +) and first round of implementing the tool at well esteemed architectural offices in the Nordic Countries. The development of the real-time LCA-indoor climate- energy balance tool was developed by funding from the Nordic Built Foundation.