To illustrate this point, let us investigate the best means of heating hot water with scenarios at the extreme ends of the energy price and carbon spectrum. If energy was very expensive and came predominantly from fossil fuels, then efficient hot-water heating technologies such as heat pumps or thermal-solar systems would make a lot of sense in terms of paybacks, lower electrical demand and reduced carbon emissions. On the other end of the spectrum, if energy were to be hypothetically free and completely renewable, efficient hot-water heating technologies would never make sense.

At some point on this continuum, a tipping point is reached. The question is, has this point been reached with rooftop PV at the current price? Analysis reveals that for, multi-unit residential and office buildings, it has indeed.

Solar Panel Array (Credit: MaxPixel)

Looking past the bad reputation that resistance hot-water heaters have gained, in part due to the lone prescriptive hot-water heating clause in SANS 10400 part XA, they have various advantages over solar-thermal or heat-pump systems. These advantages include:

• reduced maintenance
• simpler reticulation
• lower installation cost
• reduced space requirements
• silent operation
• easier concealment

Solving the problem of matching demand and production

In a conventional residential development, the economics of solar PV have been precarious given the absence of a feed-in tariff. Daytime peak solar output does not coincide with morning and evening demand peaks. Batteries are a solution to this, but their high price usually eliminates them as an option.

But what if there were another way? By coupling resistance water heaters – timed to heat mostly during daytime solar production peaks – with rooftop PV, one can use geysers as thermal batteries. Electrons that would otherwise have gone to waste are used to heat water.

Regulatory compliance

In deploying a rooftop PV system with geysers and timers to ensure peak production is absorbed by the geysers, there is a hurdle: the aforementioned energy regulation of SANS 10400 Part XA excludes resistance heating as an option for domestic hot water.

Comically, if interpreted at face value this allows one to light a diesel fire under a boiler, but not to power a geyser with 100% renewable solar energy.

Fortunately, this clause has been successfully challenged at building councils, where the improved environmental and economic performance of rooftop PV combined with timed resistance geysers has been demonstrated by way of rational assessment.

To meet the energy regulation, we have to show that at least half of the energy used to heat hot water comes from solar PV. This is not an onerous amount of PV and, in fact, the economics of it incentivise the developer or homeowner to maximise rooftop PV. In doing so, the submission is in line with the overriding regulation that states the intention of SANS 10400 Part XA: To reduce greenhouse gas emissions.

Analysis: Capacity generation

Analysis has shown that, for a given investment, a developer can buy more generating capacity by using a grid-tied PV system (and using geysers timed to heat water during daytime hours) rather than a solar hot-water system. The same applies when comparing this system with PV and heat pumps, assuming a set investment.

In other words, viewed at system-level, a given amount of money will produce better environmental performance if spent on grid-tied rooftop PV and geysers than if it were spent on alternative hot water heating technologies. This unexpected result has everything to with the declining price of rooftop PV, a trend that is set to continue.

In the details

If specifying such a system, attention must be paid to the thermal properties of the geyser. We now have a resistance-geyser energy labelling standard, and it pays one to pay a premium for a properly insulated geyser that scores well on this scale.

It is worth noting that in the absence of a minimum amount of rooftop PV, a geyser on its own will not be compliant with SANS 10400 XA. Similarly, it will not deliver good financial and environmental performance.

Viewed another way, using geysers to utilise excess solar power during the daytime production peak actually enables and incentivises developers to maximise PV area on residential rooftops.

To enquire about using geysers on projects that have rooftop PV installations, contact info@sans10400xa.co.za for details on a rational assessment of such a system.

The post The Return of the Geyser appeared first on Solid Green Consulting.

Excellence in design for greater efficiencies

EDGE Experts encourage the construction sector to design and build green by serving as trusted and experienced advisors. EDGE Experts are able to: provide clients and professional teams with a greater understanding of bioclimatic design and green technologies through their skills, insights and thorough understanding of the EDGE software; provide a cost-benefit analysis of green concepts, systems and solutions that best match the client’s aspirations; and assist the client in imagining and realising an entirely green portfolio.

Energy efficiency simulation in the design of homes

Energy modelling has been shown to be one of the best-value tools in saving energy. Solid Green has now developed a solution that uses bespoke software and automation to provide architects with answers to all the most common questions on any residential project, to provide a solution that is energy efficient and thermally comfortable.

Sun Path Diagram

Results are quantified and presented for every room in the house, and the associated cost of heating and cooling is anticipated to give clients real metrics by which to make decisions. In this way, the cost of Energy Efficiency Simulation is radically reduced, while maintaining the quality of predictive information to the client.

Solid XA:Online

Solid XA was designed to allow specifiers to quickly and easily create and manage residential projects for SANS10400 XA Rational Assessment. The app is used to: input details for walls, glazing, roofs and floors; upload building plans; and enter client’s invoicing details. Through this easy-to-use system, multiple projects can be managed, and materials profiles can be saved for reuse later. Once all steps have been completed, the assessment is speedily performed by Solid Green.

To find out more about our services and products for residential projects, or to see how your residential project will perform before it’s built, reach out to us at hello@solidgreen.co.za.

The post Support for Residential Certifications appeared first on Solid Green Consulting.

Starting from initiation, design and construction, Solid Green‘s service offerings extend right through to operation and maintenance of a project. Marloes Reinink, founder of Solid Green, says:

Ideally, green-building consultants should be involved from the initiation and design stages of a project to maximise the cost efficiency of green-building initiatives. This includes working with the client to create a green-building brief that encompasses the vision for the project. Services then extend to: green-building workshops and project-strategy sessions; setting targets for environmental performance and/or benchmarking of sustainable design, construction and operations; energy, thermal and daylight modelling; and Green Star aspiration.

Solid Green Consulting has tailored its service offerings to meet the needs of its clients in this environment, taking into account the best building practices, the long-term financial and operational benefits of going green, and the increasing demand for systems that benefit occupant health and productivity.

Solid Green is specialised and experienced in both Green Star and LEED green-building certification, offering certification for offices, multi-unit residential projects, retail centres, industrial developments, existing buildings, interiors, and public and education buildings. All team members are Green Star SA Accredited Professionals, with key team members also holding LEED AP accreditation.

Certification services

• Certification workshops, courses and education.
• Strategy and risk assessments for certification projects.
• Certification consulting and management.
• Specification and material review.
• Peer review of certification submissions.

To enhance its offerings, Solid Green has developed an innovative web app called Solid XA to take the hassle out of completing and submitting SANS10400 XA Rational Assessments. For the operational phase of a project, live-metering software has been developed to display real-time energy- and water-consumption information online.  Building user-guides are then also made available to tenants and the public via a website – ensuring that building occupants understand the importance of the green initiatives that have been implemented.

The post Implementing a comprehensive green vision appeared first on Solid Green Consulting.