Facing SAP 2016 revisions
Part of the revision of SAP 2012 enforces the change of building regulations concerning CO2 emissions. They must now be reduced by 23%, from the current value of 517 g/kWh to 399 g/kWh. This revision focusses on refining and updating the existing calculation methodology and will be known as SAP 2016 (although yet to be formally published).
All-electric buildings do not contribute to local air pollution, and it is for this reason that heat pumps are often the technology of choice, becoming the new default low-carbon energy solution.
However, heat pumps are limited in the way they can be deployed for modern residential building designs. The increasing trend for high-density residential towers in dense urban environments often means a 100% heat pump solution cannot physically be deployed on the site. Limitations in the available power supplies, noise limits from planning departments, availability of ground area/water source, height limits (aesthetic considerations) and availability of roof space for external plant all often squash projects before they have begun.
The obvious design choice here is to try and mix the technologies, using a bit of gas and a bit of heat pump. This makes perfect sense from a building design perspective but there is a hidden hurdle - SAP. If SAP detects any use of gas for heating, even as low as 1%, it changes the fuel factors to gas and therefore moves the TER to the gas rate. So a site using 99% heat pump is treated the same as a site with 100% gas.
Combining gas and heat pumps into the same mechanical system has its challenges, but luckily solutions to those problems are now being launched into the market. The Zeroth Energy System is one such way of integrating the technologies to the best benefit of the building design.
The Zeroth system provides heating, cooling and hot water services to residential or commercial spaces using a network of heat pumps. These are then connected to an energy loop, which is a water circuit maintained at between 15⁰C and 25⁰C and is, in turn, maintained within operating parameters using centralised heating and a cooling plant. The heat pump in each apartment or commercial space can then be connected to a range of emitters including fan coils, radiators, underfloor heating or fan convectors. Hot water is provided by a localised cylinder, which is charged by the heat pump.
Systems like this provide the solution to meeting the SAP 2016 criteria and prove to be an effective, energy-efficient heating solution for both residential and commercial buildings.