The Problem: Uncontrolled Heat Loss From Open Water Surfaces
An uncovered or poorly covered heated water surface loses energy through four mechanisms: evaporation (typically 60–80% of total heat loss), radiation, convection, and conduction. In process applications like anaerobic digesters, biogas lagoons, and heated treatment ponds, this heat loss directly translates to higher boiler fuel consumption, lower biological activity, reduced biogas yield, and inconsistent process temperatures.
A non-insulated floating cover addresses evaporative and convective losses by physically separating the water surface from the atmosphere. An insulated floating cover goes further — it adds a layer of thermal resistance (measured in R-value) that reduces conductive heat transfer through the cover material itself. The question is not whether covers work, but how much thermal resistance your application actually requires.
Where Insulation Matters — and Where It Doesn’t
Applications That Typically Require Insulated Covers
- Anaerobic digesters — mesophilic (35°C) and thermophilic (55°C) digesters lose process heat rapidly to cold ambient air, reducing biogas production and requiring supplemental heating
- Biogas lagoons — covered lagoons generating biogas must maintain temperature for methanogenic bacteria to remain active through winter
- Heated process ponds — industrial process water held at elevated temperatures for chemical reactions, cooling loops, or thermal treatment
- Cold-climate wastewater treatment — biological treatment processes that slow or fail when water temperatures drop below critical thresholds
- Aquaculture in cold regions — fish and shrimp farms maintaining tropical species at 26–30°C in northern climates
Applications Where Non-Insulated Covers Are Sufficient
- Evaporation control on ambient-temperature reservoirs — no heated water to protect; the cover’s physical barrier is enough
- Algae suppression — blocking sunlight is the mechanism, not thermal resistance
- Potable water protection — preventing contamination and UV degradation of chlorine residual
- Bird and debris exclusion — physical barrier function only
- Odor reduction on unheated lagoons — surface coverage suppresses volatile emissions without thermal requirements
Technical Comparison: Insulated vs. Non-Insulated Floating Covers
The table below compares AWTT’s full product range across the criteria that matter most when deciding whether insulation is warranted for your application.
| Criterion | Non-Insulated Covers | Insulated Covers |
|---|---|---|
| R-Value Range | R-0 (no thermal insulation) | R-4 to R-17+ |
| Heat-Loss Reduction | 40–60% (evaporative & convective only) | 70–95% (evaporative, convective, & conductive) |
| Best Application | Evaporation control, algae suppression, potable water, odor reduction | Anaerobic digesters, biogas lagoons, heated process ponds, cold-climate treatment |
| Operating Temperature | −57°C to +71°C | −57°C to +71°C |
| Surface Coverage | 91–99% | 98–99% |
| Wind Resistance | Up to 130+ MPH (Hexprotect® AQUA) | Up to 90+ MPH (Rhombo Hexoshield® 189) |
| Cost Tier | $ – $$ | $$ – $$$ |
| Energy Payback | N/A — no thermal savings to recover | Typically 1–3 years on heated applications |
Product-by-Product Breakdown
Non-Insulated Products
| Product | Geometry | Coverage | Wind Rating | Best For |
|---|---|---|---|---|
| Armor Ball® | 100mm sphere | 91% | Sheltered | Budget evaporation control, sheltered ponds |
| Armor Ball® AQUA 275 | Water-ballasted sphere | 91% | 75 MPH | Moderate-wind sites, cost-effective coverage |
| Hexprotect® SLIM | Lightweight hex tile | 99% | Sheltered | High-coverage sheltered applications |
| Hexprotect® AQUA | Self-loading hex tile | 99% | 130+ MPH | Best all-around non-insulated, potable-safe |
Insulated Products
| Product | R-Value | Coverage | Wind Rating | Best For |
|---|---|---|---|---|
| Hexprotect® MAX R | R-17+ | 99% | Sheltered | Maximum insulation, digesters, extreme cold |
| Rhombo Hexoshield® 66 | R-4 | 99% | 130 MPH | Insulation + wind resistance, exposed heated ponds |
| Rhombo Hexoshield® 189 | R-8 | 99% | 90+ MPH | Highest insulation with wind resistance |
Decision Framework: When to Specify Insulation
Use this framework to determine whether your application warrants the additional cost of an insulated floating cover — or whether a non-insulated cover delivers everything you need.
Specify Insulated If:
- The water is heated above ambient temperature and you are paying for that heat (boiler, heat exchanger, steam injection)
- Biological processes depend on temperature — mesophilic or thermophilic digestion, nitrification in cold climates, or aquaculture species with narrow thermal ranges
- Ambient temperatures regularly drop below 5°C and the process cannot tolerate the resulting heat loss
- Energy cost justifies the upgrade — if the annual heating cost saved by insulation exceeds the incremental cover cost within 1–3 years, insulation pays for itself
- Biogas yield is a revenue stream — temperature drops reduce methanogenic activity and directly reduce biogas output and revenue
Non-Insulated Is Sufficient If:
- The water is at ambient temperature — there is no heated process to protect
- The primary goal is evaporation reduction, algae control, or contamination prevention — these are physical barrier functions, not thermal functions
- The site is in a warm climate where the delta between water and air temperature is small year-round
- Budget is the primary constraint and the application does not generate energy savings to offset the higher cost of insulated covers
Why AWTT: Full Insulation Range From a Single Vendor
AWTT is the only floating cover supplier offering a complete thermal spectrum from R-0 (no insulation) through R-17+ (maximum insulation) — all in modular, maintenance-free, UV-stabilized HDPE formats. This means:
- One vendor for any thermal requirement — no need to source insulated and non-insulated covers from different manufacturers with different material chemistries, warranty terms, and installation procedures
- Mix and match on the same site — deploy Hexprotect® MAX R over your digester and Hexprotect® AQUA on your adjacent storm pond, with a single purchase order and consistent installation methodology
- Engineering support for thermal modeling — AWTT can calculate the heat-loss reduction and energy payback period for your specific geometry, climate zone, and heating costs to determine the right R-value specification
- 25+ year lifespan across the full range — insulated and non-insulated products share the same UV-stabilized HDPE construction with zero maintenance requirements
Key Specifications at a Glance
- Armor Ball® — 100mm sphere, 91% coverage, sheltered sites, lowest cost per m²
- Armor Ball® AQUA 275 — water-ballasted sphere, 91% coverage, 75 MPH wind rating
- Hexprotect® SLIM — lightweight hex tile, 99% coverage, sheltered high-coverage applications
- Hexprotect® AQUA — self-loading hex tile, 99% coverage, 130+ MPH wind, NSF/ANSI 61 potable-safe
- Hexprotect® MAX R — R-17+ insulation, 99% coverage, maximum thermal protection for digesters and extreme cold
- Rhombo Hexoshield® 66 — R-4 insulation, 99% coverage, 130 MPH wind (water-ballasted), hybrid geometry for heated ponds
- Rhombo Hexoshield® 189 — R-8 insulation, 99% coverage, 90+ MPH wind, highest insulation with wind resistance
All products are manufactured from UV-stabilized HDPE, rated for −65°C to +70°C operating temperatures, and carry a 25+ year expected service life with zero routine maintenance. Full technical data sheets are available on each product page.
Frequently Asked Questions
When does a floating cover need insulation?
Insulation is necessary when the water temperature must be maintained above ambient — typically in anaerobic digesters, heated process ponds, biogas lagoons, and cold-climate aquaculture systems. If the primary objective is evaporation control, algae suppression, or bird deterrence on an ambient-temperature water body, a non-insulated cover is sufficient and more cost-effective.
What R-value do I need for an anaerobic digester?
Most anaerobic digesters operating at mesophilic temperatures (35°C) in temperate climates require at least R-8 to maintain process temperature without excessive supplemental heating. In cold climates with sustained sub-zero ambient temperatures, R-17+ (Hexprotect® MAX R) is recommended to minimize heat loss and reduce boiler fuel consumption. AWTT engineering can model the heat-loss calculation for your specific digester geometry and climate zone.
Can I use a non-insulated cover on a heated pond?
A non-insulated floating cover will still reduce heat loss from a heated pond by suppressing evaporative cooling and blocking convective airflow across the water surface. However, without thermal insulation in the cover itself, conductive heat loss through the cover material remains significant. For heated ponds where energy cost is a factor, an insulated cover typically pays for itself within 1–3 years through reduced heating energy.
Do insulated covers resist wind as well as non-insulated covers?
Wind resistance depends on the product design, not the presence of insulation. The non-insulated Hexprotect® AQUA resists 130+ MPH winds through self-ballasting. Among insulated covers, the Rhombo Hexoshield® achieves 95+ MPH wind resistance with its hybrid geometry and partial self-ballasting. The Hexprotect® MAX R, which provides the highest insulation at R-17+, is designed for sheltered applications. AWTT can help match the right combination of insulation and wind resistance for your site.