The challenge

Social Justice – most renewable energy solutions are capital intensive hence they are in reach only to the financially advantaged part of the society. Household Electrification – executive decision has been made to gradually phase out natural gas as means of heating homes in the Netherlands. Acoustic Discomfort – one of the most promising alternatives to replace heating by natural gas are Air Source Heat Pumps (ASHP). It’s a problematic piece of equipment in regards to noise emission. Retrofit – most ASHP solution in the market today are not suitable for retrofitting into existing high temperature hydronic heating systems. The Looks – heating equipment that litters built environment’s facades and/or roofs is rarely considered a thing of beauty.

The solution

In order to allow the part of society that is usually unable to afford capital intensive sustainable solutions to be able to obtain an opportunity to do so it is important to lower the capital costs. This can be done by offering the solution in question as a service - Smart Stack does just that. It offers heating as a service. This means that the capital investment is dealt with by the company that owns the hardware – in this case Smart Stack. The client simply pays a monthly subscription fee and does not worry about the technicalities. For some clients it can also be an added bonus that the service uses renewable grid energy. Mostly it is the competitive pricing that majority of clients are going to find greatly appealing. Smart Stack is a subscription based heating service, which sets the entry bar low and allows major part of the society to afford these renewable energy based services hence resolving the social injustice. Smart Stack is the alternative to heating that can minimize household electrification impacts on the electrical grid infrastructure. With the executive decision to gradually phase out the use of natural gas for indoor space heating there is going to be a shift to alternative means of heating. One of them will be electricity based heating. This will increase the demands on the electricity grid. The increased loads on the grid will require huge investments into infrastructure and measures will have to be taken in order to use existing grid more efficiently – Smart Stack does just that. Peak shaving can allow better utilization of the existing grid – strategically (by switching on or off) using high electric load appliances when there is surplus (or deficit) energy in the grid. This also means that overall better electricity prices can be arranged in this way. Do to the unpredictable nature of renewable energy these peak times often coincide with times when there is a lot of renewable electrical energy available in the grid. So running ASHPs on these times financially benefit Smart Stacks in two ways. The purchased electricity is cheaper and peak shaving services can further lower the costs of electricity. By taking into consideration that households are usually empty during daytime and that it’s during this time that renewable energy electricity surpluses occur the Smart Stack can be run during the day and charge the Phase Change Material (PCM). Then in the evening or morning when there is demand for domestic hot water the heat can be silently extracted from the PCM. The ASHP can be run when nobody is home, which means that noise nuisances are lessened. Acoustic discomfort generated by some ASHPs are off putting. Very few people want to hear the sounds of a rattling white box late at night. It’s a frequent complaint made by ASHP owners – the equipment occasionally generates a lot of noise. Taking into consideration that during heating season the coldest time of the day is the night then this nuisance can quickly escalate into a problem. Smart Stack runs ASHP preferably during the day when electricity is cheap (due to Solar) and stores the heat in PCM thermal buffer. When the stored heat is extracted from the PCM no noise is generated. This ensures the peace of mind of the clients. The acoustical comfort levels can also be adapted by the smart thermostat coupled to the Smart Stack. As the device learns user preferences gradually the nuances will be completely eliminated. On their own ASHP are struggling with legacy high temperature hydronic systems present in many households. By using PCMs as a thermal buffer the water can be heated to higher temperatures enabling retrofit into existing household heating systems. As a result little has to be adapted if a resident decides to use Smart Stack’s heating services. Few ASHP solutions that are available in the market today are suitable for retrofitting into legacy heating systems. The water temperatures that are generated by most ASHPs are too low for existing high temperature hydronic heating systems. PCMs are able to heat water to higher temperatures than ASHP alone hence Smart Stack can be retrofitted into houses with existing hydronic high temperature systems. Smart Stack integrates neatly into the traditional looks of a house by being incorporated into the chimney. HVAC equipment boxes littering built environment’s facades are rarely considered captivating. Smart Stack has the ability to integrate this equipment into an archetypical part of a house (that is losing it function) – the chimney. External equipment integration into the roof also provides easy access for hardware installation, maintenance and deinstallation. By using a familiar archetype the appearance of the house is preserved. By means of standardised modules the exterior shell of the Smart Stack can be adapted to suit the existing architectural aesthetics. If the client decides that the Smart Stack service is no longer required the system can be uninstalled by simply lifting it off the roof of the house. Intention is that these are going to be rare occurrences. Smart Stack hardware is going to be designed according to C2C principles, so with ease of maintenance, longevity, and reusability in mind. Due to modularity and standardization of the system the hardware will be refurbished, new exterior shell applied and reused on the a new site.

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