A LEED Strategy...
GAS TECHNOLOGIES just as advantageous as geothermal energy?
When we think about sustainable development, LEED certification certainly cannot be ignored. The usual objective of such certification is, of course, to reduce a building’s ecological footprint on its environment and, ideally, its greenhouse gas (GHG) emissions. So, what’s our first reflex? To want to remove natural gas from the energy picture at all costs, even though it’s the fossil energy that emits the least GHGs. Well, think again! LEED certification is not intimately linked to geothermal energy. Look at these results with natural gas – it’s an alternative that should not be disregarded.
Gaz Métro gave consulting firm Bouthillette Parizeau the mandate to analyze various solutions in terms of both economy and economic performance. The results:
A building that uses natural gas can easily achieve pre-requirement 2 (EAp2i) in the LEED Canada Energy and Atmosphere category for new construction and major renovations. Also, points are obtained at low cost for Credit 1 (EAc1ii) in the same category. Learn about the three buildings included in the study:
- an 8,200 m² residential and long-term care centre (CHSLD)
- a 5,700 m² office building
- a 6,000 m² mixed-use building (offices and warehouse)
Case study: CHSLDFour solutions analyzed
In the first case study, four solutions were analyzed, based on the parameters shown in Table I
. An energy simulation was carried out using these parameters, while also considering certain parameters common to all the solutions.Table II
shows the energy performance obtained for each solution. Based on the objective sought by the building owner, the choice of technologies varied.Solution 1 - First level of certification
In fact, if the goal is to obtain a LEED Certified building (first level of certification), opting for Solution 1, which offers energy savings of 35% compared with MNECB 97, may seem attractive. However, this result is misleading: because the reference building uses natural gas, adding electric baseboard heating on the perimeter results in savings in terms of gigajoules, but not in operating costs, as required by LEED. Also, with an all-electric solution, the building could not achieve the energy performance required and EAp2 would be difficult to achieve without additional measures.Solution 2 - an alternative to Solution 1 in opting for hot water heating on the perimeter
As well as easily achieving EA pre-requirement 2, a point is obtained under EAc1. The energy saved in monetary terms is 27%; 29% in energy performance. This solution calls for an additional construction cost of more than $100,000 (see Table III
), but the savings total almost $24,000 a year.Solution 3 - Better economic and energy performance
Solution 3 seeks both better economic and energy performance using everyday, albeit high performance, gas technologies. In fact, condensing boilers have been used in Québec for many years and the advantages of underfloor radiant heating are well know. This solution may seem costly at first sight (additional cost of $290,000 - see Table III
), but the savings achieved are about $43,000 a year, which translates into a return on investment (ROI) in six years, without any subsidies.
As well, 3 points are obtained under EAc1. If we compare with geothermy...
Lastly, if we compare this solution with the one that uses geothermal energy (Solution 4), the study results show us that, besides having an additional capital cost of almost $430,000, geothermal generates somewhat lower savings in operating costs, without offering more points for EA Credit 1. However, it should be noted that the two solutions are not necessarily technically comparable since Solution 3 (gas and condensation) makes use of a high-efficiency heat recovery unit to achieve overall building performance at least equivalent to that offered by Solution 4 (geothermal). Given that 1 LEED point has the same value no matter what the credit, it thus becomes advantageous to opt for a solution that uses natural gas with a lower investment cost and that offers results similar to geothermal.
Unlike the CHSLD case study, all three solutions use just one source of energy for heating needs (natural gas); there is therefore no hybrid solution (gas/electricity). On the other hand, the results are the same. In fact, as indicated in Table IV
, the use of conventional natural gas technologies shows just how easy it is to obtain basic LEED certification (LEED Certified) by meeting EA pre-requirement 2. The comparison between additional capital costs (Solutions 2 and 3) indicates an extra outlay of about $400,000 in Solution 3, while operating costs are to the advantage of natural gas in these two solutions.
In the third case study, intermediate gas heating is clearly the most advantageous solution. The low additional cost for the same number of LEED points makes it the best solution by far.
The study conducted by Bouthillette Parizeau demonstrates that traditional gas technologies, combined with heat recovery systems, have earned a place in a LEED certification strategy, plus they compare advantageously to the option that uses geothermal integrated with an all-electric solution.See Table V