Converting an Existing Building to the Low Temperature Hot Water District Heating System

Building heating systems accounts for a substantial part of the energy consumption on campus. Therefore, the development of a more sustainable heating system such as LTHW district heating will allow the campus to transition from using fossil fuels to future sustainable energy sources.

As such, the goal of this project supports the university’s climate action plan of becoming a carbon-neutral campus by 2050.  LTHW district heating allows for the integration of renewable energy and waste energy sources and reduces the heat losses in the system increasing the system efficiency. Moreover, the renovations required for the integration of LTHW make the existing buildings more energy-efficient and promote energy savings.  

Our design solution allows for the ICT building to fit the requirements of the 4GDH, which is the latest stage of district heating. This is a pilot project that the University of Calgary is starting, heading towards a carbon-neutral campus by 2050. Moreover, our design solution allows for the use of existing piping; therefore, no major re-work of the building is required.

This is an innovative design that allows for the successful integration of LTHW in the ICT building. It will lower the building heating load while ensuring thermal comfort is maintained. This solution can be installed in a relatively short period of time, allowing for minimal disruption to learning and everyday use of the building. 

To determine the design solution for the project, different universities that converted their campus to the LTHW system and their successful retrofit strategies were researched. Passive and active retrofit strategies were explored that can potentially be implemented in the ICT building to accommodate for LTHW district heating. The passive strategies include insulating and sealing appropriately, and the active strategies include adding additional heating units, such as radiant panels, to the critical zones.

The model was used to determine the effectiveness of each retrofit solution and if the building’s heating system functions adequately when the supply water temperature is lowered. The model results suggest that with this design solution, the ICT building can be operated at 70°C and the energy consumption has been reduced by 14.6%. Therefore, it can be confirmed that by adding the suggested retrofits, the ICT building heating system can be converted to LTHW district heating system.

Softwares such as SketchUp, OpenStudio and Energy Plus were used to model the ICT building. To determine the accuracy of the model, the energy consumption data provided by the model was compared to the real-life energy consumption data of the ICT building. There were no major discrepancies between the two sets of data. In addition, the results from the model met the accuracy criteria suggested by our technical advisor Dr. Simon Li. Based on this, it was concluded that the model is relatively accurate and the results can be considered valid.

Once the model was complete, the retrofit solutions were simulated. This was done by changing the specifications of heating equipment such as water temperature and flow rates and adding additional equipment, as necessary. Construction of the exterior walls was modified to mimic the effect of adding loose-fill insulation in the exposed gaps. Improvements in the window insulation were simulated by changing the North and West double pane windows to triple-pane windows. After running the simulation with the retrofit solutions, the new heating data was analyzed to see if it was more energy-efficient and if the building is still sufficiently heated. 

Economic feasibility analysis was performed to examine and investigate the investment and return on investment associated with the LTHW district heating incorporated in the ICT building. The analysis compared the performance of the ICT building as designed without LTHW district heating and the retrofitted ICT building with LTHW district heating using a 50-year net present values analysis. Sensitivity analysis was also performed to identify 70°C as the most suitable supply temperature. 

The analysis shows that the LTHW district heating offers a net present value savings of $1.5 million over 50 years with a payback period of 14 years. Figure 1 shows the cumulative profit flow of our design solution. Figure 2 shows the 50-year NPV savings of our design solution compared to the conventional design.