The first rule of sustainability is to align with natural forces, or at least not try to defy them.

Paul Hawken

 We often use Paul Hawken’s quote to start or end our presentations to clients and project teams. By following this ethos, we believe we can create spaces that are more aligned with nature and can therefore achieve more than we think is possible.

While our goal was always to ensure that our office building adheres to the levels of sustainability we advocate, a bit of misfortune pushed us to really test the boundary of just how much we could align with nature. Our office construction project started just before the onset of the hard lockdown due to Covid in 2020. The site sat with a half-demolished building for over eight months and, in this time, the municipal meter and infrastructure were stolen.

This pushed us to install our solar system much earlier than anticipated and also drove the decision to stay completely off the grid. There is often some confusion between net-zero and off-grid: you can be net-zero without being off-grid. In our case, we are net-zero because we are off-grid. Our only source of power is the sun.

Our office can accommodate all 20 of our staff members. With remote work, the actual numbers vary from 5 to 15 in the space at any given time. Each staff member has a laptop and a screen, and our 4 modelling team members work off desktops with two screens each. Despite this, our installation is smaller than one that would usually be installed in a 4-person home.

Natural Hours of our building

Energy in our office is used primarily for the delivery of our services, namely to power equipment like computers. Not needing energy for lighting or comfort means our building is able to run only on power available from the sun.

 We are an ‘A’ whichever way you look at it.

Energy performance certificate (EPC) benchmarks have recently been updated. This is causing some concern in the industry as the new benchmarks, shown in red, are significantly lower than the old benchmarks, shown in blue. Even taking the new updates into account, our office still outperforms an ‘A’. This shows what can be achieved if energy for comfort and lighting is reduced significantly. Particularly for offices.

The journey is not without its challenges. Our backup is only a 5kWh battery. That is enough to power your geyser at home for only 2 hours. Our original installation was 6,450W solar panels – enough power to turn on the electric element in a geyser. We eventually added additional panels (12 x 180W, they were tiny) that had been taken from our old office. This almost doubled our capacity and improved our ability to continue working on low sun days.

A key problem was that, if the battery was very low, we needed more energy earlier in the morning. We faced the additional panels slightly east to remedy this, ensuring that we get more energy early in the day if the battery was empty from the day before.

The battery is large enough to keep the fridge and security system running overnight with no issues. We have controls that switch off all monitors, TVs, printers and lights at exactly 6-30pm every day. We have always advocated for our team to have a good work-life balance, so we expect the office to be empty by then. External security lighting is all solar lighting that has its own integrated battery.

Our biggest challenge comes if we have two consecutive days of no sun. Even with direct sunlight, our solar panels generate a small amount of power and, because we only need a small amount of energy, this can keep us going through the day with the help of the battery. No sun days, however, means our battery does not charge and so the second day of no sun requires some load management. Like Eskom, we have a few levels of load management (to prevent shedding):

• Stage 1 – Turn off fridge, TV and non-essential kitchen appliances unless using them. Items like kettles and microwaves can be used for a very short space of time because they tend to be high power but low energy.
• Stage 2 – All kitchen appliances are switched off and cannot be used.
• Stage 3 – All kitchen appliances plus all screens are switched off and cannot be used, except for the modelling team.
• Stage 4 – All kitchen appliances plus all screens are switched off and cannot be used, except for the modelling team. When battery gets to zero, go home.

In 18 months of occupation, we have had stage 4 only once. Even stage 1 is rare. We only need the sun to peek from behind the clouds for an hour or so to alleviate any issues.

Challenges and future plans

 Living with nature cannot always be perfect. Johannesburg is cold in winter and, while the passive design interventions employed in our office mean that we have not required cooling in summer, we do need a heating solution for cold winter mornings. Our challenge is that it needs to fit within our current energy budget and we do not want to increase the solar production or battery backup to accommodate heating. We believe we have found a solution that meets this requirement and hope to have it in place in time for next winter.

That will be a story for another day though…

The post Our New Office: Chapter 10 – targeting Net Zero appeared first on Solid Green Consulting.

The main challenge was the roof. It was leaking badly and had a weird maze of parapets. We decide to take off the roof completely and replace it with a new timber structure, similar to the main building. This gave us the opportunity to demolish all the internal walls inside and create new dividing walls. While adding the new roof we were reminded of the difficulty of working with old structures – not a single wall was straight! We had already ordered the window frames and windows, as well as the kitchen, as part of the main building order. So, we made the openings in the building fit the window frames that we had.

The incessant rain this summer did not really help the construction process. The plaster dried slowly, and the planned four weeks had to be extended to six weeks. In the meantime, the team was working from home and Activate Architects was kind enough to host us at their offices for a couple weeks.

We also added a big tank for rainwater harvesting as we hope to eventually move off grid in terms of water supply as well as electricity supply. Of course, we will have to rework our garden again as it took a bit of a knock during construction, but we hope that it will come right in the spring of 2022.

Now that we have done the final leg of the construction we hope to finally settle in the coming months. One of our major accomplishments with the office is that it is running 100% off our solar panels on the roof and is completely independent from the municipal electricity supply. We have had a couple of days in the last 8 months where we had limited electricity due to a number of cloudy days in a row but, overall, the solar panels are sufficient to accommodate us.

We look forward to finally settling in, and to really making 33 6^th street Solid Green’s home for many years to come.

The post Our New Office: Chapter 9 – The Multipurpose Space appeared first on Solid Green Consulting.

On (over)sizing solar systems

As feed-in-tariffs exist in a minority of locations in South Africa, this also means that there will often be times when a system produces more energy than a building uses. Whether it’s an office generating energy on a weekend which cannot be used, or a residential building generating power that is lost when no one is home at midday, the problem of forfeited energy is widespread.

Even where feed-in-tariffs exist, they only pay a fraction of the grid price of energy to the private producer. While batteries represent a solution to this, they require high capital cost and essentially let you offset excess energy at what you would have paid to buy it from the grid.

A new kind of mining

Satoshi Nakamoto* invented Bitcoin in 2011. A new kind of internet money, Bitcoin does not rely on central banks or governments to maintain trust in the system. Instead, proof of work uses computational power to verify transactions in a public ledger in a process called mining – and miners are rewarded with new Bitcoin minted through this process. At its most basic, energy is used to run computers which then produce Bitcoin as a reward.

A virtual arms race emerged from this system, whereby more and more powerful hardware was required to mine Bitcoin. In the early days – circa 2012 – multiple Bitcoins could be mined per day using a laptop. The price of Bitcoin at the time of writing is R16 500. The global Bitcoin mining network currently uses more energy than the whole of Denmark, drawing some sustainability concerns. It is apparent, however, that the incumbent banking system is far less energy efficient by requiring offices and travel. As a result of this immense competition, it is no longer economical to mine Bitcoin using conventional hardware.

Enter altcoins

Bitcoin is not the only option, however. Hundreds of other cryptocurrencies born of the same recipe exist, and are often called “altcoins”. Like the early days of Bitcoin, they are still economical to mine with desktop computers.

At Solid Green, we ran an experiment using Solid Insight to monitor energy usage. For 1 kWh of energy used by computers mining altcoins, you get about R1.30 as a mining reward. This is almost exactly the purchase price of the energy. As such, mining off grid power yields no profit… But what if you have excess solar power that was to be wasted because you could not sell it back to the grid?

Excess solar power would normally be fed back to the grid for free. Using it to mine cryptocurrency yields a surprisingly high profit.

Mining that uses existing idle computer hardware with excess solar power is commensurate with selling power back to the grid at the same price that it costs to buy power. This is around three to four times the fee you will get from the grid if you could sell your excess power. As solar PV is so much cheaper than grid power, this results in a profitable proposition – far more economical than installing batteries or relying on a feed-in-tariff.

The trick lies in only mining cryptocurrency when excess solar power is produced. We achieved this relatively simply with Solid Insight. Monitoring our solar production vs consumption is ongoing, so we only needed to run simple software that would use our computers to mine when our solar production was greater than office consumption. This way, we were essentially able to produce currency at grid parity with our excess solar power.

While this may sound trivial, the implications are very important. The payback of a solar installation can be reduced by a significant amount, making it worthwhile for more of the market sooner, bringing us closer to energy independence and a sustainable energy future.

*The identity of Satoshi Nakamoto is one of the mysteries of Bitcoin. He/she/it may be a person, or a group of people.

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