Ambient loop heating: focusing our (district) energy on sustainability
Strategic positioning of meters and accurate billing of an ambient loop heating and cooling system has potential to realise low to negative carbon opportunities. By monitoring and targeting the energy produced, consumed and traded/exchanged within an ambient loop system, energy service companies, building owners and tenants would benefit from potential cost saving opportunities.
Sweco’s Energy and Sustainability team along with their building service colleagues are in the process of delivering a solution for accurate metering and billing of a communal synthetic peer to peer thermal trading system. Several water source heat pumps serving tenants connect to the building’s ambient heating and cooling loop.
What is an ambient loop heating network?
An ambient loop heat network system is best defined and applied in the context of mixed-use development. As, a variety of mixed-use buildings provided an ideal opportunity for the installation of a site-wide ambient district energy network that is set to provide benefits in terms of reduced energy costs and carbon emissions.
Large mixed-use developments have enough thermal energy flows generated by human activity to provide the base for both heating and cooling of the entire site. By connecting buildings with different needs and balancing the energy between them, effectively using all available energy flows makes it possible to decrease both pollution and the energy consumption on the proposed site.
Individual buildings connected to the system would generally use localised heat pumps and cooling machines, exchanging energy with the network. Each building makes energy deposits or withdrawals from the district energy grid, which means that the energy demands from all the buildings are best balanced against each other. Energy is only added or removed from the system when off-balance occurs.
The buildings on the site are connected with a single set of flexible pipe grids that distributes thermal energy flows. Therefore, the system is classed as “district energy” instead of “district heating and cooling”, as a single set of network pipes provide for heating & cooling demands for individual buildings. In addition, the ambient-temperature nature of the system not only minimises losses but also maximises the ability to captive traditionally discarded low-grade waste “heat”.
The ambient energy network allows for an energy strategy based on all-electric apparatus that will have no on-site NOx emissions. It also tackles the heat island effect by absorbing most of the waste energy from the buildings cooling system. The urban heat island effect created by building cooling rejection systems are often ignored. The reduction of waste heat rejection will benefit the well-being of the end-users and directly tackle localised overheating in an urban environment.
Metering and Billing Model
Sweco are in the process of modelling a method of accurately billing the tenants for use of the ambient loop served by the landlord air source heat pump and associated circulation pumps.
For each water source heat pump within the tenant’s demise, the model uses data from bi-directional heat meters provided at tenant branch connections in order to determine the tenant’s water source heat pump mode of operation.
At any given time, the water source heat pumps could be in one of the three following modes of operation:
• Heating Mode: Utilising energy from the ambient loop for heating
• Cooling Mode: Rejecting energy into the ambient loop for cooling
• Passive Mode: No heating/cooling demand within the apartment
The final output of the model is a break down of apportioned costs to each tenant for using the landlord air source heat pump and associated circulation pumps, calculated using the energy consumption and operating mode data.
System schematic showing flow meter and temperature meter locations
Potential Energy, Carbon and Cost Savings
Modelled data highlighting periods where energy is traded between apartment heat pumps can be used to determine opportunities for cost savings and reduction in the overall operational carbon footprint. This also enables opportunities to incentivise tenants as part of promoting energy efficiency and carbon savings.
For more information, or to request modelling for your own building please contact Kartik Amrania – Head of Building Sustainability.
We bring the well-established low carbon energy solution from Scandinavia for energy solutions in the UK. Our ability to integrate our sustainability consultancy services throughout western Europe has allowed us to draw lessons and initiate out-of-box thinking on our projects. Our market-leading and award-winning building sustainability team in the UK is part of the wider Sweco sustainability teams operating across Sweden, Denmark, Norway, Finland, Germany, Poland and the Netherlands. We are a single team when it comes to sustainable-by-design, which is the ethos of our consultancy.