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# HRV Energy Recovery Efficiency Explained
Every HRV and ERV spec sheet lists four or five efficiency numbers. Most homeowners (and many installers) do not know which one matters. This guide walks through the metrics, what they mean for Toronto winters and summers, and how to read a quote with the right context. For the pillar guide, see [HRV & ERV Installation Toronto: The Complete 2026 Guide](/blog/hrv-erv-installation-toronto-2026-complete-guide).
The Four Metrics
1. Sensible Recovery Efficiency (SRE)
The percentage of heat retained between the exhaust and supply streams. The headline number on most spec sheets.
How it is measured: HVI (Home Ventilating Institute) tests the unit at 0 C outdoor and 21 C indoor at the rated CFM. The formula accounts for fan heat and case losses.
What is good: 70 percent SRE is acceptable; 80-85 percent is the typical premium tier; 88-92 percent is high-end.
2. Apparent Sensible Effectiveness (ASE)
The simpler heat-recovery percentage that does not account for fan power and case losses. Always higher than SRE for the same unit.
How it differs: ASE is the textbook calculation; SRE is the real-world net.
What is good: ASE is a marketing number. Use SRE for comparisons.
3. Latent Recovery / Effectiveness (ERV only)
The percentage of moisture transferred between exhaust and supply. ERV-specific.
How it is measured: tested at summer conditions (35 C / 50 percent RH outdoor, 24 C / 50 percent RH indoor) and winter conditions.
What is good: 50-60 percent is typical; 65-75 percent is premium.
4. Total Recovery / Effectiveness (ERV only)
Combined heat and moisture transfer expressed as effective enthalpy recovery.
What is good: 70-80 percent for a competitive ERV.
What the Numbers Mean for Toronto
Winter Heat Recovery
A typical Toronto January day: -10 C outdoor, 21 C indoor. Temperature delta of 31 C across the core.
- 70 percent SRE: incoming air pre-heated to about 12 C.
- 85 percent SRE: incoming air pre-heated to about 17 C.
- 90 percent SRE: incoming air pre-heated to about 18 C.
Across a Toronto winter (about 4,500 heating degree days), the difference between 70 and 90 percent SRE is roughly $35-$80 per year on a typical home's heating bill. Real but not life-changing.
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A typical Toronto January day: outdoor absolute humidity is very low (about 1.5 g/kg). Indoor at 21 C and 35 percent RH is about 5.5 g/kg.
- HRV: incoming air arrives at outdoor humidity (1.5 g/kg). Indoor RH drops as the moisture is exhausted.
- ERV at 60 percent latent recovery: incoming air arrives at about 4 g/kg, much closer to indoor humidity. Indoor RH stays steadier.
This is why ERVs are the typical Toronto choice in 2026.
Summer Latent Recovery (ERV only)
A typical Toronto July day: 28 C / 70 percent RH outdoor (about 16 g/kg), 24 C / 50 percent RH indoor (about 9 g/kg).
- HRV: incoming muggy air hits the home directly. AC works overtime to dehumidify.
- ERV at 60 percent latent recovery: incoming air pre-conditioned to about 11.5 g/kg. AC has less work to do.
Across a Toronto summer, the AC energy savings from an ERV (versus HRV) is about $25-$55 per year. The bigger benefit is comfort: indoor humidity stays in the 45-55 percent range without spikes.
For the head-to-head, see [HRV vs ERV Toronto: Which to Choose](/blog/hrv-vs-erv-toronto-which-to-choose).
Why HVI Ratings Matter More Than Manufacturer Claims
The Home Ventilating Institute (HVI) tests units to a standard protocol and publishes the results. Some manufacturers list both HVI numbers and their own internal numbers; the internal numbers are typically optimistic.
When comparing quotes, ask for:
- HVI Certified Performance Rating sheet for the model.
- SRE at 0 C and -25 C if available.
- Latent Recovery at summer conditions if ERV.
- Sound rating (sones) at low and high speeds.
A unit not HVI-listed should be a yellow flag.
Real Numbers for Toronto's Top Three Brands
| Model | SRE at 0 C | Latent Recovery | Sound (sones, low) |
|---|---|---|---|
| Panasonic Intelli-Balance 100 ERV | 90 percent | 65 percent | 0.4 |
| Panasonic Intelli-Balance 200 HRV | 88 percent | n/a | 0.5 |
| Lifebreath RNC 10 HRV | 78 percent | n/a | 0.8 |
| Lifebreath 200 ATH ERV | 84 percent | 55 percent | 0.7 |
| Venmar AVS HEPA HRV | 80 percent | n/a | 0.9 |
| Venmar AVS HEPA ERV | 78 percent | 50 percent | 0.9 |
| vanEE V100H HRV | 75 percent | n/a | 0.9 |
For the brand head-to-head, see [Panasonic vs Lifebreath vs Venmar HRV](/blog/panasonic-vs-lifebreath-vs-venmar-hrv).
The Cold-Climate Adjustment
Almost every published efficiency number is measured at 0 C outdoor. At -25 C, two things change:
- Frost defrost kicks in. Recirculation defrost pauses ventilation 4-8 minutes per cycle, dropping average CFM 10-15 percent.
- Pre-heat defrost uses 500-1,200 watts of resistance heat, cutting net efficiency.
A unit rated 88 percent SRE at 0 C may deliver 75-80 percent effective SRE at -25 C across a continuous run. The premium pre-heat units (Panasonic Intelli-Balance) hold steadier through the deep cold.
For frost management, see [HRV Condensation Prevention Toronto Winter](/blog/hrv-condensation-prevention-toronto-winter).
How Efficiency Affects Operating Cost
Putting numbers together for a typical Toronto detached home (2,000 sqft, 3 bedroom, 4,500 HDD per year, 100 CFM continuous ventilation):
- Annual ventilation heat load (HRV at 70 percent SRE): about 980 kWh equivalent gas.
- Annual ventilation heat load (HRV at 85 percent SRE): about 540 kWh equivalent gas.
- Annual ventilation heat load (no recovery, exhaust-only): about 3,300 kWh equivalent gas.
The difference between 70 percent and 85 percent SRE: roughly $30-$45 per year at current Enbridge rates. The difference between recovery (any HRV) and exhaust-only: roughly $200-$280 per year.
The first dollar of efficiency (going from no recovery to any recovery) is by far the largest savings. Going from a budget HRV to a premium HRV is a smaller incremental gain.
Fan Power: The Hidden Cost
Continuous ventilation runs the HRV fan 24/7. Fan power matters.
| Unit Type | Continuous Power | Annual kWh | Annual Cost (5 cents/kWh) |
|---|---|---|---|
| ECM low-watt (Panasonic) | 35-50 W | 310-440 | $15-$22 |
| ECM standard (Lifebreath ATH) | 60-90 W | 530-790 | $26-$40 |
| PSC (older units) | 100-160 W | 880-1,400 | $44-$70 |
The ECM motor advantage is real and persistent.
Recovery Versus Filtration
A common confusion: efficiency numbers do not measure filtration. A 90 percent SRE unit with MERV 8 filtration is still passing pollen, fine dust, and small particulates. For allergy households, the filtration spec matters more than the SRE delta.
Premium tier: HEPA on supply (Venmar AVS HEPA, Panasonic Intelli-Balance with HEPA add-on). Mid tier: MERV 13. Standard: MERV 8.
What Toronto Homeowners Should Actually Care About
In rough order of importance:
- 1. Filtration spec (especially for allergy or near-traffic).
- 2. Sound rating at low speed (continuous-running unit; 0.5 sones beats 1.0 sones).
- 3. HVI-listed SRE (anything 80 percent or higher is competitive).
- 4. Defrost strategy (pre-heat for tight high-occupancy homes; recirculation acceptable for most).
- 5. ERV latent recovery (60 percent or higher for Toronto climate).
- 6. Fan power continuous (ECM, not PSC).
- 7. Smart-home integration (if the home has it; a nice-to-have).
A unit that hits 4 of these 7 is fine for most Toronto retrofits. A unit that hits 6-7 is premium.
Final Word
Efficiency numbers matter, but the spread between competitive units is smaller than the marketing suggests. The biggest win is going from no balanced ventilation to any recovery system. After that, filtration, sound, and defrost strategy are typically more impactful than the last few percentage points of SRE. RenoHouse coordinates the unit selection with HVAC-licensed installers based on the home's IAQ priorities, occupancy, and rebate strategy.
Book at [/services/hvac-energy/hrv-erv-installation](/services/hvac-energy/hrv-erv-installation). For deeper reads, see [HRV & ERV Installation Toronto: The Complete 2026 Guide](/blog/hrv-erv-installation-toronto-2026-complete-guide), [Panasonic vs Lifebreath vs Venmar HRV](/blog/panasonic-vs-lifebreath-vs-venmar-hrv), [HRV vs ERV Toronto: Which to Choose](/blog/hrv-vs-erv-toronto-which-to-choose). Related: [HVAC Thermal Audit (FLIR)](/services/inspections-diagnostics/hvac-thermal-audit).
