Green construction is a very broad concept that encompasses all stages of a building’s life cycle, from conceptual design to operation and maintenance. In general, green construction deals with minimizing the total energy footprint and environmental impact of a building.
A building can be green starting from the construction process, by minimizing waste and environmental impact. Green construction is strongly influenced by the design and planning stage: if a building is specified by qualified engineering professionals, and then planned considering best practices in project management, waste is minimized because there are less surprises and change orders during the process. Another aspect of green construction is the use of materials that have a low environmental impact, both on-site and during their production.
With respect to building operation, there are three main approaches to reduce the environmental footprint. They complement each other, achieving great synergy, and the best results are obtained if these features are added to building before it is commissioned:
- Energy efficiency consists on minimizing the total energy consumption of a building. In commercial buildings, the most cost-effective upgrades are those that focus on improving HVAC systems, followed by LED lighting retrofits.
- Energy management focuses on managing energy consumption patterns to achieve the lowest operating cost. Building automation systems can achieve excellent results when combined with energy efficiency upgrades, potentially duplicating energy savings.
- Renewable energy sources allow buildings to self-generate the energy they need, partially or fully. Solar water heaters and photovoltaic panels are among the most common options in commercial buildings.
The main difference between energy efficiency and energy management is that the first concept deals with the amount of energy consumed, while the second deals with the time when it is consumed. Utility companies normally charge rates that vary by the hour and increase in proportion with power grid demand: consuming one kilowatt-hour during off-peak hours is less expensive than doing so during peak demand.
This article will provide some tips to achieve the best results with green construction.
1) Green Materials and Sustainability Reduce the Impact of the Building Process
Green construction starts from the building process, and there are many practices you can follow to mitigate the environmental impact at this stage:
- Purchase locally-produced materials whenever possible. This reduces their emissions and environmental impact during transportation.
- Incorporate recycled materials such as reclaimed lumber, and whenever possible use natural materials such as bamboo or cork. With respect to new materials, use recyclable products when possible. Also, look for materials that come with recyclable packaging.
- Look for certifications that guarantee materials have been extracted and processed responsibly. This is especially important for lumber.
- Incorporate products that will reduce the building’s environmental impact in the long term, such as low emissivity windows and insulated concrete forms.
2) Green Technologies are More Cost-Effective in New Constructions
The best time to carry out green upgrades for a building is during construction. Retrofitting or upgrading systems in existing buildings involves changes to current installations, and this involves extra costs, especially when a piece of equipment is replaced completely. In new constructions, there is already a baseline cost to assume, and any green upgrades only represent an incremental cost beyond what would have been paid anyway.
As an example, to illustrate this concept, assume a building owner is choosing between a conventional resistance heater and a heat pump:
- The resistance heater has a lower cost but is outclassed by the heat pump in terms of efficiency. An air-source heat pump typically provides savings of over 60 percent, and a ground-source model may save 75 percent or more.
- In an existing building, the cost of the upgrade is the full price of the heat pump plus any associated labor, as well as the cost of decommissioning existing equipment.
- In a new building, on the other hand, the upgrade cost is only the price difference between both types of equipment, plus any difference in labor costs.
- Also, consider that the electric current drawn by a heat pump is lower, which may allow its feeder circuit and protections to be sized smaller, providing additional savings upfront. In an existing building, these savings are not available – the existing circuit ends up being oversized after the upgrade.
This does not mean green upgrades to existing buildings are a bad investment, far from it. However, the financial return of these measures is higher in new buildings.
3) Green Construction Provides Synergy Among Building Systems
One of the best features of green construction is that the benefit of different technologies working together is normally better than the sum of the parts. Therefore, a developer that integrates multiple green technologies into a new building right from the start can expect a drastic reduction in ownership costs.
Consider lighting and air conditioning systems, for example. If a commercial building uses LED lighting, savings in the range of 30 to 40 percent can be expected, compared to conventional fluorescent lighting. In the case of air conditioning, energy efficiency depends directly on the energy efficiency ratio or coefficient of performance, both of which are a ratio of cooling output to power input. However, when both measures are deployed in the same building, the following effect occurs:
- Upgrading the lighting system saves energy directly, but also reduces heat emissions.
- With a lower heat emission from the lighting system, the cooling load on air conditioning units is also reduced. In large buildings, this may represent several dozen tons or refrigeration capacity.
- This way, the air conditioning system can be sized smaller in addition to being energy efficient.
There are many examples of how green technologies can achieve synergy in commercial facilities; this is just one possible scenario. In a few words, green building upgrades provide much better results when deployed together.
4) Building Envelope Upgrades are Considerably Cheaper During Construction
An efficient building envelope is one that keeps heat inside during the winter and outside during the summer. This is accomplished by minimizing heat transfer across walls, windows and ceilings, as well as air leakage.
The main advantage of an efficient building envelope is that it saves energy and reduces the building’s environmental footprint, while having no operating costs. However, since the building envelope is part of its structure, upgrades can be very expensive in existing buildings, making it difficult to justify the investment. On the other hand, these upgrades only represent an incremental cost in new constructions; building envelope improvements are perhaps the energy efficiency measures with the highest cost increase when deployed in an existing construction, compared to a new one. If budget is a limitation for green technology upgrades in a new building, giving priority to building envelope measures is strongly recommended.
5) Get a Professional HVAC Design
Even if you purchase the most efficient HVAC equipment in the market, your building will not achieve maximum performance unless the installation is properly designed and specified. Improperly sized HVAC installations suffer from performance and efficiency issues, and this applies for both undersized and oversized systems. Avoid the selection of heating and cooling equipment based on “rules of thumb” – they often result in equipment that is two to three times larger than required, which is more expensive upfront and more expensive to operate.
The energy efficiency of HVAC equipment is displayed in their nameplates. For air conditioning, look for the highest Seasonal Energy Efficiency Ratio (SEER) available; and in the case of heat pumps take note of the Heating Seasonal Performance Factor (HSPF). Alternatively, look for the Coefficient of Performance (COP), which applies for both types of equipment. In heating systems that use combustion, look for the Annual Fuel Utilization Efficiency (AFUE). All these metrics are like the gas mileage of a car, where a higher value translates into lower costs. Just keep in mind that, to compare two pieces of equipment, the efficiency must be reported with the same metric for both.
6) Personnel Training is the Complement to Green Construction
The energy rebound effect occurs when the potential savings of an energy efficiency or renewable energy upgrade are not fully achieved due to behavioral factors. For example, the personnel in a commercial building can become more careless about lighting and HVAC use if they know both systems are highly efficient.
Training staff on energy efficiency practices is the best way to compensate the energy rebound effect. This can be complemented with a green building certification, such as LEED or ISO 50001, turning energy efficiency into an ongoing business process.
Green construction involves the entire life cycle of a building, not only the construction process. Although it involves additional upfront costs, green construction minimizes the cost of ownership and environmental impact in the long term. The best time to incorporate energy efficiency, renewable energy and environmental sustainability measures into a building is during project construction: this reduces the cost of these measures, while maximizing their financial return.