There’s increased awareness today about net-zero construction. We know that new buildings can be designed and built to have negligible to no emissions during regular operation. Green building regulations which are now commonplace in more than a few countries ensure that new buildings can be smart and function at peak efficiencies. We also have green certifications such as LEED, Energy Star, Estidama, DGNB, BREEAM, GSAS, IGBC, and several others that lay guidelines for how these ‘modern green habitats’ must be built. Although major roadblocks do exist in the form of fully green concrete or cement for 100% carbon-free construction, it can definitely be argued that we are at least on the right path when it comes to green construction. However, if the globe intends to go net-zero before 2050, simply ensuring that all new buildings are green won’t suffice. Mandatory green building codes only contribute a small portion of super-efficient buildings to the overall ‘building stock’. Buildings constructed more than 10 years ago hold a major share of all greenhouse emissions caused by the building operations sector.  We need to convert the bulk of our existing old and inefficient buildings into ones that consume less energy and resources. We need to make them ‘passive’. That’s where DERs OR Deep Energy Retrofits come in. Deep Energy Retrofits are development/renovation projects that significantly reduce (by more than 50%) the energy consumption of buildings. DER projects are usually conducted by ESCOs (Energy Service Companies) which specialize in the development of such activities.

What are passive buildings?

Passive building design encompasses elements in layout and form that minimize the need for artificial cooling, heating, ventilation, and lighting. Passive buildings utilize natural ventilation and natural lighting to reduce energy costs. In addition, they also focus on reducing thermal loads or cooling/heating demands by making use of tight thermal envelopes to maintain thermal equilibriums in built structures for long periods. Once all inefficiencies have been ironed out, the remaining energy consumption is covered by renewables- resulting in a net-zero building.

Deep vs Shallow retrofits

Building owners often try to go for the low-hanging fruit by employing only partial retrofits with low upfront costs and short payback periods. With short-sightedness of this sort, we’re inviting imminent doom. Partial renovation or ‘shallow retrofits’, which reduce energy consumption by 10-20% may look good on paper in the short term but over the life of the building, the costs tend to add up and be more expensive. Studies show that over the long term, this approach almost always turns out to be more expensive than deep energy retrofits. If funding capital-intensive DERs seem difficult, owners should instead opt for different combinations of energy efficiency measures that can be implemented over a longer duration with the end goal of net-zero in mind.

Technologies to achieve deep energy retrofits

1.      Building envelope

A building envelope is defined as a separation between the conditioned and unconditioned portions of a structure. It is the skin that envelopes the whole building protecting it from the environment. When all walls and exposed surfaces are well insulated without any thermal gaps, a building loses or gains thermal energy from outside very slowly. This means that once a space is heated or cooled, it stays that way for a long time. Basically, you turn your building into a giant thermos flask that keeps heat in. An airtight and ‘thermally tight’ building can get away with using far less energy because once the spaces are conditioned, it only needs incremental conditioning to keep it that way. A proper envelope also reduces the load on HVAC equipment, increasing their lifespan and thereby increasing savings.

2.      Windows

Solar heat gain through windows is a double-edged sword. In winter you need to maximize solar heat gain through windows to save on heating costs. In summer you need to block as much of it as possible to reduce air conditioning costs. With proper planning, fenestration can help you save a lot in unnecessary conditioning. Double, triple, or even vacuum glazed windows available today can help achieve significant savings by eliminating heat loss through them.

3.      Smart Lighting

Replacing old light fittings with LEDs is the easiest lighting retrofit that can be done. These retrofits are simple to perform. The savings are also apparent and estimated results can be calculated with ease. In addition, if the lighting system is retrofitted with motion and occupancy sensors, with smart controls unwanted lighting can be switched off to save more energy.

4.      Optimised cooling and heating

HVAC systems typically contribute to over half of a building’s energy needs. Well optimized HVAC systems can be up to 50% more efficient compared to their lazy counterparts. HVAC optimization can be achieved by using advanced AI deep learning technologies or even by simply retrofitting systems with VFD controls.

5.      White Roofs

Paints with high reflectivity or SRI (Solar Reflectance Index) can reduce the heating up of building roofs by the sun’s rays. White roofing is a fairly cheap means of reducing heat load in buildings. High-quality white roof coatings have been shown to reduce surface temperatures by as much as 20 degrees!

6.      Renewables

Once the building’s energy consumption has been reduced to the bare minimum, whatever is left can be powered by renewables. This could be solar, wind, or any other sustainable source of energy suitable for the property. As renewables make the last step, the building can now be made 100% passive or net-zero.

Scaling up retrofits

In most cases, it’s easier to build a new energy-efficient building than to retrofit an old one. But the goal of net 0 by 2050 does not give us that liberty due to the sheer number of old buildings present. Though numerous technologies like the ones mentioned in the previous section exist today, scaling them up is the real challenge. High capital costs associated with several options drive building owners away from taking such risks. The dearth of government policies aiding efficiency projects combined with a lack of awareness suppresses adoption rates of novel technologies. Energy retrofits shouldn’t be limited to a few companies trying to achieve their CSR goals. We should look for ways to take advantage of economies of scale. In Netherlands for example, the EnergieSprong standard utilizes mass-produced prefabricated insulation to quickly retrofit buildings. Technology and business innovations like these can go a long way in the mass adoption of energy retrofits.

Future of efficient buildings

With solar and wind power getting all the limelight right now, it’s easy to get carried away and think that novel renewable sources of energy can save us. It couldn’t be further from the truth. You can’t just have a dirty, old, inefficient structure that chugs energy and make it green by slapping on some solar panels on top. The production process of solar panels themselves causes emissions. Transporting the panels to construction sites will then cause some more emissions. The first few months of clean energy production will be enough to just offset the emissions caused during the installation process. Furthermore, all buildings may not even have space or resources to be powered by solar or wind. Even ignoring the challenges associated with the intermittent nature of solar and wind, scaling up renewable sources to power the entire world will be a mammoth task. With global air conditioning set to triple by 2050, the task at hand only gets bigger.

One major way we can make scaling of renewables easier is by increasing efficiencies across industries. Use less energy to begin with so that you end up having to offset less of it to renewable power. Building energy efficiency mandates such as the ‘Future Homes Standard’ in the UK or the ‘UAE Energy Strategy 2050’ which aims to reduce energy demand are good starting points for this issue. Deep Energy Retrofit is a great way of drastically reducing energy consumed by buildings. Remember, the cleanest kilowatt-hour is the one you don’t use.